Hi Handcrafter
I often get this questions from my clients when they want to start a blog. As I see it there are 3 alternatives.
New domain
We typically recommend this option when the blog might loose credibility by being on the main company domain. You also might want to have a different style and tone on the blog. Say a bank wants to start a personal finance blog for teens. The language and tone used here might not reflect the values and tonality used on the main bank website. There could also be a value in this due to the possibility of linking in a smart way between the two domains.
Good: Freedom in the way you communicate, links between the two domains
Bad: Takes long time to get pagerank and domainrank, confusing message to the user
Subfolder
Using a subfolder is the direct opposite to using a separate domain. Its integrated with the site and will be perceived by the users as part of the site. In my opinion style and language should, at least partly, match that of the main website. Search engines will most likely also see the blog as part of the site. Dependent on the domainrank of the main site it might be easier to get a good pagerank for the blog in a short amount of time.
Good: Integrated to the site, one channel, easier to rank on
Bad: har to use different tonality. Can be tricky to use different CMS or publishing tool.
Subdomain
Using a subdomain can be seen as a mix of the both above. It allows for a different technical setup and a somewhat different style and tone. If you have a strong main domain you will have an easier time to rank compared to a completely new domain.
Good: can use different technical setup, somewhat easier to rank on
Bad: Not as integrated as a subfolder, not as free as a new domain
Normally we advise our client to use a subfolder due to the SEO benefits. But only when:
- Their technical environment can handle it
- The blog does not use credibility by living inside the main site
- Style and tonality is somewhat the same
- The main domain has an already established domainrank
You mention security concerns as your main reason against using a subfolder.
Maybe you can elaborate on this a bit?
Have a great day
Fredrik
PS you can find a bit further info here:
http://www.michielgaasterland.com/blogging/integrating-your-blog-with-your-main-website-choose-subdomain-or-subdirectory/