I like to keep my HBFP's stock, I don't crash very often so I don't worry about breaking stuff I just don't want to put any unneccesary money into it if I don't have too, got other things to sink money into
But a modded HBFP with metal upgrades will fly better then with the stock plastic parts. If you plan on only having and flying the HBFP and Belt CP for a while then it would make sense to upgrade it a bit, but if you plan on getting a BIG heli like the ES600 (E-Smart) or any 500 size then save all the money you can and don't buy anything you don't need unless its for your big heli, just my opinion but bigger is better and a hell of alot easier to fly
Thats why you only see me doing loops and rolls with my ES600 and not my Belt CP V2, the difference in stability is unreal
Also, oddly enough I find it easier to fly my HBFP V2 then my Belt CP V2, not sure why but its always been that way for me