I really don't think there's any "right" or "wrong" way to go about this. As Ray said, this is a very, very small aspect of your on-page SEO and shouldn't take up too much of your time in terms of worrying.

When in doubt, ask yourself "will this make sense from my reader's perspective?" On average, if you follow that line of thought, you won't go far wrong.

If you are hitting the 200-300 comments/page mark it might be better to get into pagination from a sheer UX perspective - depending on their dedication to the content matter, it is unlikely that the average user is going to want to sift through so many comments after reading your content.

I don't know what audience you are targeting, but it seems to me that 25-50 would be sufficient to capture the essence of most commenting sections regardless of topic and would also help with loading times.

Ray makes a great point about the canonical tag and rel tags though - as with everything, your strategy has to account for your specific situation and marketing approach.

Hey Eric,

No, you're right. If that's the degree to which your content is diverging, it may be necessary to have 2 completely separate domains. One set does not have anything to do with the other, and that will absolutely affect relevance and compatibility when it comes to linking practices.

You could go with a subdomain structure and diverge your link profiles - it would have much the same effect as going with 2 separate domains. That being said, it makes life really difficult if you are moving domains or redirecting in the future, so a subdomain structure is pretty permanent and not ideal if most links are coming back to your Home Page.

You could attempt a social media bridge for both sites, but that may be a bit beyond what you are trying to accomplish here. I think you have the right of it based on the facts presented.

Here's wishing you the best of luck on the shift!

Best,

Rob