You said your opponent was a maniac. Did you have a big sample size, or did he play really out of line? I am asking this because sometimes the opponents get really good cards all the time and that makes them seem like maniac when in reality, they are not.

I would never fold this against maniac. In my opinion it is a good idea to let the maniac bluff his chips to you.

I think I still prefer betting the flop on this board texture simply because of how wet it is. If I'm not betting this I'm going for a check/raise. There are many, many combos with equity on this board and you don't want to give away free cards.

As played the board becomes absolutely atrocious and unless villain is unbelievably aggro I'd consider folding on the river.