Hobbywing 120A v2.0 uses 24 pieces On semiconductor NTMFS4833N Power MOSFET (~HK$7 each in bulk buying) which can stand 30V maximum but the capacitor provided is only 16V max. NTMFS4833N is commonly used in top quality of ESC such as LRP TC Spec, Mamba, etc. HTC LM39302 is used for linear BEC output.
Changing higher voltage of capacitor and use external BEC, maybe we could use 4S-6S Li-po, I use 4S A123 with no problem using the existing 16V capacitor.