Well, even I thought so about it. I don't know the exact amount you'll be receiving in BTC for selling your hash power and if that's greater than or equivalent to ETH mining but it seems a bit lucrative for now and this dips temp, so what-ever you choose, you're good to go. Moreover, Selling your rigs hash for a contract will be more profitable than nicehash itself.
Yeah, selling rig hash for a contract definitely sounds more profitable. Have you done this before?
Im curious actually, is there an online service that can automate selling hash between you and a client?