If I go with XenForo, it will be for a project that requires a heavily customized skin, and for this I just don't think the admin panel editing tools or the webdav option really cut it. In my experience using WebDAV is overly clunky, slow, and just downright a pain to use (even when doing local development). I do my development on a Mac and own both Transmit and Coda 2, which are often cited as being the preferred way of interacting with webdav on mac, but even with these, the workflow is far from optimal.
Is there any chance of just plain old local file editing for styles (even if its just in a debug/dev mode option) being added in the near future? If so, that would definitely seal the deal for me.