Just wanted to chime in and add my experience with both providers.

To be clear, Yext is more expensive. It also is a direct feed into more listings. If you are trying to get listings published quickly and need to show results (or reports) to a client, Yext would be a better way to go. As a subscriber, you can also give your clients discounts from the Yext pricing page, which can help add to your overall total commitment from the client. As far as data being removed, the additional data that is added via Yext's api is no longer valid or displayed once you stop paying (they call it no longer a "trusted" listing). I have never had one revert back to a pre listing status. Yext uses one of the many large databases: Factual. Chances are that by submitting to factual the other data aggregators will pick up your listing with time, even if you have not submitted to them.

Moz local is a great resource for companies that have the time to wait. The data aggregators they submit to take time to publish the listing. Acxiom, Nuestar and the others can sometimes make it confusing or even very expensive to list on their data networks. Acxiom is one of the stronger databases, having been known to be a direct feed to Google.

My advice:

If you can afford to wait the 2-3 months to have the listing start to appear, then use Moz. The time period you have to wait is not necessarily the fault of Moz, as even if you submit directly to Acxiom yourself it will take 2-3 months to go live. Ultimately, your listing will appear on the other citation sites, it will just take longer to do so.

If you are looking for an additional source of income and are a great salesman, use Yext. Yext has a much better interface of showing how many listings are incorrect, (even if many of the ones that are listed are from their own proprietary citation sites. ). This makes it an easier sale to your clients, and also easier for you as an agency to get an idea of how bad your clients current citation status really is. Yext will get your listings posted very quickly, and give you a place to link to off of your main domain, giving your clients additional sources of validation very quickly. Some of the sites they submit to are a bit dinky, but hey, a link and validation source is just that. Pricing is higher, but I think its fair considering the speed and extras you get for the money.

AND... the elephant in the room is of course.. do it all yourself! This will offer the most control over all your listings and control over who and what to submit where. You will lose out on some of the other benefits of MOZ (cheaper cost vs your time and long wait) and YEXT (faster speed, lots of directories but higher cost). It's worth noting that some of the YEXT directories that they are partnered with you cannot actually submit to, as they are either created by YEXT or locked so that you have to use their service to submit your listing there.

We never place a link without the site owners permission.

It's a grey area to be sure. Lots of the things that Google states can contradict one another, such as in your case: They want you to have authoritative backlinks from reliable sources, but they dont want you to pay for it. (Might get in their way of getting your Adwords dollars, lol)

In this case, look closely at what you are getting. Sites like YP, Chamber of Commerce all offer paid profile creations, with the paid profile links being of a higher visibility within their website. If you are getting a full profile page, with lots of ways for you to support your business or company then it could be beneficial. If you are getting a small, otherwise unfindable profile page with a anchor text optimized link directly to your site, I would stay away.

Think of the benefits of having the link. Is your link going to be placed somewhere it can be found, and when found, does the page that will be linking offer the user anything. How does the profile page help build upon your brand?

"If I were to pay for a profile with them, would I request for a "nofollow" link back to my site? "
Again, it depends on how they set up the profile, and how they set up their profiles for all the other businesses on that site. If Google sees the site as just a way to milk money out of people for paid backlinks, they will get hit and eventually so will you. I would do some investigating into the other businesses that have profiles on there, and see how they do in search results. Either way, one link will most likely not do a ton of damage to your reputation, but is that a risk you would be willing to take? Just boils down to what you feel comfortable with.

I am for adding the company name at the end. If a person is searching for a brand or company, you should have more than a few places where that name or brand is mentioned.

I understand that branding involves much more than this, but due to how the site is set up, I don't see anything wrong with it. You are not extending your title past the character count, not putting your name at the beginning of the title, etc. The page titles are already very short, so I see no harm in it.

With is being so easy to rip off anothers brand name with a domain or URL, I personally agree with using using a company name in the page title, unless your company name is extremely long, and jeopardizes the character count displayed.

Then, there is always this:
http://searchengineland.com/quantifying-brand-bias-search-results-rand-fishkin-moz-189824

I'm sure some will disagree with me, but that's what makes the internet such a great place. Being able to agree to disagree

You can submit them separately. One for video, one for images, one for URL's. This may be a more effective approach at getting things indexed, as it separates them into their own category. If you are already having a high load time, wouldn't hurt to try.

To answer your original question:

"Sitemaps should be no larger than 10MB (10,485,760 bytes) and can contain a maximum of 50,000 URLs. These limits help to ensure that your web server does not get bogged down serving very large files."

But wait, there's more!

http://www.seroundtable.com/archives/021559.html

"Google has changed the number of Sitemaps you can reference in a Sitemap index file. The number use to be 1,000 sitemaps can be referenced in a Sitemap index file, now the number is 50,000 Sitemaps. This is a huge increase in capacity.

Still, each Sitemap file can contain up to 50,000 URLs, so technically 50,000 multiplied by 50,000 is 2,500,000,000 or 2.5 billion URLs can be submitted to Google via Sitemaps."

I agree with EGOL. I see what you are trying to do, but I would try and capture that traffic and content for your own site, then to give it away to Wikipedia.

We had a discussion in the office today, about if it can help or hurt you to link back to your site from one that you optimize, host, or manage.

A few ideas that were mentioned:

HURT:
1. The website is not directly related to your niche, therefore Google will treat it as a link exchange or spammy link.
2. Links back to you are often not surrounded by related text about your services, and looks out of place to users and Search Engines.

HELP:
1. On good (higher PR, reputable domain) domains, a link back can add authority, even if the site is not directly related to your services.
2. Allows high ranking sites to show users who the provider is, potentially creating a new client, and a followed incoming link on anchor text you can choose.

So, what do you think? Test results would be appreciated, as we are trying to get real data. Benefits and cons if you have an opinion.

Anyone can edit a Wiki page = bad for your business. If you can't control it, or constantly have to edit what people type it's not worth the time investment.

Wiki outranking your main site =  bad for your business. Here's why: Wiki often has a ton of references and links on a page about a business. The chances that a user will click one of those and navigate away from your page is very high. Worse case would be that a user clicks a similar business, that is a competitor of yours. Think of it like having the "related videos" displayed at the end of a youtube video. They click, they leave, you are not thought of again. One thing to remember when advertising on the internet; It is your job to convince people to use your services. People that do not know your business don't owe you anything, and have no brand loyalty to your company.

Yes, I added it into OSE. That's actually where I found so many of them. You should see what is linking to this site, as it's truly scary. I would never want our domain to be a part of that. BUT, somehow it is working for them. Almost every link is something questionable, and not related at all. It's funny how Google will penalize hotvsnot and the like, but not this type of activity.