It's not that big of a step going from a coaxial heli to a 600. Oh brother, that statement alone would seem to indicate a problem. Have you flown your uncle's 450? If so, how much? I personnally found G 3.5 very helpful, but it absolutely is not the same thing. I can do inverted circuits on Realflight and have yet to do an inverted tail-in hover in real life.