You can base the weight of votes on POW. Yes AVA coin is PoS. Whatever this you are saying is speculation. I think Avalanche is awesome but I'll leave if BCH becomes PoS.
Good point. However, PoW-based avalanche is more complicated, and it does not allow miners to come and go arbitrarily as they would surely lose trust.
I don't think Avalnche becomes any more complicated if it relies on PoW, or PoS. It is it's own consensus form, and is independant of the PoW done by miners.