Walkera basically changed the name of the old 4g3 and sold it to Helimax as the Novus CP.  Despite the higher price tag, the Novus CP is using parts/technology from Jan-Feb 2009 and most of the upgrades (metal parts and the brushless motors) are all left out as separate options.  I suspect that the only testing on the Novus CP is at the Walkera Factory in China.  Most Walkera Dealers in the US have to retest the 4G3 and make adjustments when Walkera shipments arrive (I don't think Helimax / Hobby Co is going to do the extra testing for you).   If you are having tail and vibration problems you can try adjusting the Rx mention in previous posts, check the gear mesh  and make sure the main rotor shaft and it's surrounding parts are not damaged.  You can do this by holding the heli in your hand and crank up the throttle.  Look at the main rotor from the top to see if the circle between the blades is round or oval or blurred.  If it's oval or blurred than you have issolated your problem at the main rotor.
3D aerobatics, powerful accelleration, steep banking turns, tight circles are some of reasons for getting a CP heli in the first place.   For serious CP and 4g3 pilot s (that we aspire to be, lol), the Novus CP is at best a marginal aerobat.  You need the extra torque on a lighter heli which can only be achieved through simutaneous BL upgrades for both the main and the tail motors.  Because there are so many critical and expensive upgrades missing on the Novus CP, it's more cost effective to start with a new upgraded 4g3 and use the Novus CP for spare parts since the parts are interchangable.  Any ways, that is just IMO.   Here are some reliable domestic sources that I've used over the years for Walkera and Novus related helis and parts.  rotorfever.com, wowhobbies.com, heliclub.com, toysonics.com, helidirect.com.  I make most bigger purchases online (usually about 30% lower than LHS) and smaller purchases at my LHS (a quick fix for my addiction, lol ).