the dp extra has gone through about 2-4 revisions to fix some of that flutter, the newer ones come with the option for 2 aileron servos, but basically, dont fly at full throttle on downlines or even straight!
btw, check these videos out..
http://www.3dbatix.com/videos/dp330lfull.wmv
http://www.3dbatix.com/videos/dp330lfull2.wmv
dp extra with a moki i believe..