I've been evaluating the idea of shifting my forum's support requests to WP Answers in the past few weeks, and to be honest I'm still hesitant.
The actual show stopper, to me, is that there is no means to automatically tag a question as it's being asked. SE should be updated in order to make these urls fill in the tag field automatically:
(Or possibly more appropriately,
?tagnames=semiologic.) This would allow me to rely on the semiologic tag's RSS feed, and not worry about missing questions.
Assuming the above gets sorted out, I suspect that not all end-users like the SE format. A few of the less savvy ones might make no sense of the interface. (Then again, it's a small learning curve, and they've other support venues, namely phone, Skype and my ticketing system.)
Next, I'm worried that you guys would get tired of reading questions related to Semiologic. (For some reason, many of my end-users refer to WP as Semiologic, confusing my theme/plugin bundle and the underlying CMS.) That many of these end-users are paying customers might irritate a few SE users, too.
The Semiologic tag might get big and fast, btw: they blacklisted it in the WP forums when it made it into the top tag cloud. At the time, some of the WP forum regulars would also abuse the tag by assigning it the questions that now end up in WP Advanced.
Along the same lines, I'd dread that my user base would be littering the site with valid questions which are only narrowly on topic. Examples of such could be "What should I use to track affiliate clicks originating from my site?" or "Where is the WP/Semiologic installer on hub?" or "Does Semiologic play well with [enter theme or plugin name here]?".
Some of my end-users' questions may very well be entirely completely off topic. Things such as "I love/hate Semiologic/Hub/the new forum." Even if I create a special "WP Answers how-to for Semiologic users" question in meta (or a wiki page) in an effort to prevent the latter types of threads to appear, a few such questions will creep up every now and then.
My last worry is that I occasionally use my forum to make announcements. These would clearly be off topic for this site. Sticking to my blog isn't the best option for this kind of stuff, because many of my end-users hang out in my forum a lot more than on my blog, and not all of my announcements cater to my blog's visitors.
Anyway... if the default tagging via url parameters is made to work, I'm currently willing to give it a try. But only if you guys think you can cope with the above. :-)