I do not change the elevator trim after it is set for level flight. I have my CG set to allow straight and level flight at just over half throttle, both inverted and upright, and the trim is set accordingly. When I am hovering I am constantly moving both sticks in all axis'. If you listen to a tube vid with a good 3Der hovering you will notice the throttle is constantly changing and also the tail feathers are constantly moving as are the ailerons. It is my opinion, and you'll get a bunch of those on here, that you don't want the plane to be trimmed to any type of "neutral" while in a hover. It is better to be fighting the controls just a tad and that helps train your brain, to a degree, for thoughtless correction of attitude. I also agree with ThumbSkull above that inverted harriers help a bunch. Wind junkie's 30 minutes of practice a night is also good and probably the minimum needed to become proficient at the more difficult maneuvers. Take a look at this vid and you'll see the controls constantly moving and hear the throttle working. http://www.youtube.com/watch?v=gRqdMjlBo3w

As far as difficulty, the YAK 54 3D in RF G3.5 is more difficult to hover than my AeroWorks 50cc Extra 260 in real life with one exception, the real planes torque roll much more than the sim requiring more aileron to counteract. I believe my E-Flite Extra 260 480 size is somewhat comparable in difficulty to the G3.5 YAK. Good luck and remember, practice, practice, practice.