This is the exact set up I have. Netflix, Hulu+, Amazon Prime, and NHL Gamecenter. Plus I have a digital antenna for live sports (On NBC, CBS, ABC, Fox, etc.).
Only problem I have with Game Center are the blackouts which consist of any game that is nationally broadcast (this year there haven't been many of those for the Devils) and games that are played locally to where you are. I live in Orlando so every Lightening game is blacked out. I think Panthers games too but I forget right now. I just go to wiziwig and stream the games from my computer if that's the case.
Also the streams are a little behind so if you try to follow along on a message board or chat room you will read everything before it happens on your TV.
Still I think it's very worth it. As soon as HBO becomes available to buy without a cable or satellite subscription there won't be any need for cable or satellite.