[nebben]

He might push JJ/QQ if you check to him, he might not. If he bets, and you call, the end effect is the same as an open push. The difference, to me, is that he rarely calls with JJ/QQ here. So if he has you beat, it doesnt matter because you were pushing anyways, so calling is the same. If he doesn't have you beat and pushes, you were calling anyways, but he would push with more than he would call with, so youre in better shape. If he checks, you can push the turn and he will still call with a wider range than he would have on the flop.

I don't understand how, given that you are committed, a check can be worse than a raise, because it makes you better off in every sense seemingly.