Finding the right power system combination is a result of a number of factors... http://www.ecalc.ch/xcoptercalc.php is your friend. Well worth the $1 or whatever. Look for a hover throttle of ~ 45-55% (the closer to 50%, the better). In my experience, if you get a combo that hovers in that range, w/out vibes, you hardly need to adjust any AQ settings (maybe lower Tilt Rate D a bit). If you go too far outside that range, you'll definitely need to tune (eg. overpowered setups need to be made less aggressive).
-Max