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I have to disagree with Bryan, I'm afraid - I think you carry substantial risk here, and this is a tricky decision. While EMD influence is declining, it still can carry a lot of weight (and quite a bit more than sub-domain keywords). If most of your traffic is coming from those "head" terms, you may see a serious loss by moving from EMDs to sub-domains. Sub-domains have other issues, too, like fragmentation. Since the verticals are very different, Google could treat each sub-domain more like a separate domain. Then, your link equity won't consolidate AND you'll lose the EMD advantage. So, there's actually a risk of a worst-of-both-worlds scenario. Now, to be fair - consolidation can have benefits, like unifying your link profiles, simplifying your other marketing efforts (one site to promote on social media), etc.  Also, since your niches are really just different marketing perspectives on the same product, it's possible that your current sites might look a little thin to Google. In that case, consolidation could help, but "consolidation" would mean thinning out the separate pages, not just moving to one domain with a bunch of sub-domains. Whether it's better for users really depends on your customer base. Do they tend to look for chat products as a general product, and then decide how it fits their industry, or do they look for products targeted to their industry? If the latter, then the separate domains might actually be more user-friendly. Sorry, I know this is clear as mud, but I just want you to be aware of the complexity and possible issues. I would not make this decision lightly. Please note, too, that I'm generally in favor of consolidation and am not a big fan of an EMD-based strategy. We have to be realistic about what works now, though, vs. what may work in a couple of years, and I'm just concerend about the short-term impact for you. My gut reaction, long-term, is that you could build a more product-focused site that has solid landing pages for each vertical, and that each vertical may not need a sub-site. This could create a stronger single site over time. It really depends how much unique content you've got within each vertical, and how your visitors find you. Even if that's a good long-term strategy, it could still have short-term negative impact, so you have to be aware of that and able to weather it.

I did a super-quick review of your backlinks in OSE. What I saw was mainly press releases, with a few links from sites you own, and links from pages full of spam like http://www.alivincent.com/blog/post/2010/04/28/Work-Weeke280a6e280a6-when-the-reality-show-becomes-a-REALITY!.aspx I also notice that your backlinks are overwhelmingly using your target keywords as anchor text, so you may be suffering for anchor text over-optimization. My recommendation would be to focus more on higher quality, natural backlinks. Focus on SEO strategies that build your brand and focus on users. You might find http://www.seomoz.org/blog/why-big-brands-get-all-the-breaks helpful. Hope this is helpful.