The smaller they are the HARDER they are to fly (reasonably true in all types of Helo).Yes Real Flight has saved me thousands... the set up is critical (especially on a TREX 450), as Blue Drifter says you must have them set up for trim, balanced and well tracking blades or it will all go wrong very easily. This can't be stressed enough...
Even a perfectly set up T Rex 450 will slowly oscillate around a little. Unlike fixed wing you NEVER stop working the controls, for example if you pitch nose down you cant just expect the the nose to pitch up when you release the stick like a plane would... Sold all my kit to help by the Drifter... Getting motivated for another reading this