Nice info, half a year ago I would have tested this, but now, with the new q2a release I do not see any advantage to use wp.
And there is more, in q2a there are missing just very few basic features and I believe that with version 1.5 everything will be included (like flag, some kind of communication, better "my activities" management, subscribe feature and may be some additional kind of sorting questions within others).
From 1.6 on, I believe, q2a will become really innovative with several new highly sophisticated features and functions.
I stay with q2a and i hope to be able to offer one or more custom themes to our community soon, as I think that the stackoverflow style is not everybodies liking.
WP-answers comes late, too late in my opinion.