For me, I'd think the following two main criteria would have to be met for me to consider it: 1. Something akin to IP Connect/Database connection/sharing between multiple forums. Really, I find the concept very much a fascinating and potentially useful one (much easier and better than trying to build a ton of forums from zero members) and IPB's current solution is literally the only off the shelf solution on the market. Hence why I'm probably going to be buying another IPB license for my next two forums or so. If XenForo implements something like this (or even a proper system where multiple forums all use the same database and member/post tables and settings), then I'll probably go out and buy it immediately. 2. Official add ons for a gallery, downloads and blogs. I don't lose features when I change software, so I'm likely not going to convert my current site until another script can offer these with official support and a converter. But other than that, I think XenForo seems like great software, and heck, I do plan to use it for a site in future. It'll just be one about a different topic that has no connection to my current ones due to the fact it'll be more logical/reasonable to 'start from scratch' so to speak. So yes, if you don't already own a XenForo license/use it, what features are the reason why?