You should avoid adding any aftermarket modifications to the helicopter when are are learning to hover. The reason for this is:
If you crash the helicopter, you may destroy your expensive aftermarket modifications
You will be distracted by trying to avoid destroying your expensive mods and therefore learn slower
The modifications to avoid when learning to hover are:
Carbon Fiber frames/crutches/tailbooms (cracks)
Aluminum frame upgrades (bends, increases radio glitches)
Carbon fiber frame upgrades (cracks, increases radio glitches)
Aluminum head upgrades (bends)
Fuselage (cracks)
Some mods are recommended because they improve control and are less likely to be damaged in a crash, such as:
Aluminum swashplate
Tail servo mount
Carbon fiber pushrod (only costs ~$3 to replace anyway)
Autorotation gear (REQUIRED for most brushless motors)
Ball-in-swash modification (improves control)
but in general, a stock helicopter is recommended.