Any chance you have a speed poker (like Rush, Zoom, Zone) coming SOON?
You could probably save a lot of hassle by going straight for 6 max, as all other versions at those other sites don't get much action.
Also there is an opportunity for WPN because Merge seems to have abandoned the micro stake non-HE tourneys, like HORSE and the Studs.
You could start these with NO guarantee. Horse players just want to be playing. Merge made the mistake of trying to force growth and offered guarantees that were nearly always a losing proposition. Don't bother with the guarantee. If only 4 players find them on a daily basis, they will spread the word. $2 and $5 buy-in's. Depending on how you present the games, they might grow faster, but speed of growth is not all that important.