To expand on Rafael's answer, if you are interested in flying inverted its best to have the CG under the main shaft. Any trim you have in upright in the elevator will be reversed when inverted and is a nusance to smooth aerobatics.
Been doing inverted hovers with my "beater" Raptor 50. It's the one with stock head and tail rotor parts. The other day I felt brave enough to go inverted with my 1, the one with metal head, bird cage, and upgraded tail section. When I half rolled to inverted, the nose pitched down (up? Toward the ground.) dramatically and very quickly. Caught me totally off guard and I nearly wrecked. I've found that I go inverted with it but I have to anticipate this unexpected plung.
Maybe I need to look at the CG?