Are you sure Black has enough compensation after a continuation such as 8.Qg3 Nc6 9.Qg7 Rg8 10.Qh6 e5?

Chevalier,

Welcome to the Chess Pub!  I've read a few of your messages and already I can see that you have a nice, deep sense of what you want in your chess games.

My short answer to your question is that the Romanishin Gambit is certainly going to score well in tnmts, at least up to the 2300 level.  I imagine you already have an arsenal for lines that don't include 4.Qc2. 

I had always thought that White needs to consider ...c5 at almost every point of the 4.Qc2 Nimzo.  If Black plays it, he had better be prepared, but White will know instantly that you are ready for a fight.  My instinct is to prefer 8...0-0, but I imagine that 8...Nc6 will score well for you if you put some serious work behind it. 

I don't know that 8...Nc6 will do well as the only move in your repertoire.  This is the move that should be kept as a surprise weapon.  I feel (and that's all it is, a feeling) that White could come up with something nasty and end up with a clear advantage in the endgame.