I don't think that his drinking makes him stronger than opening the gates. What the drinking instills is that it opens up another side of Lee. One that we've never seen before. As everyone has said before, Lee has pretty much been a linear character i.e. he was taijustsu based. Drinking just makes his taijutsu more multi dimensional. I don't believe that it is stronger than the gates. It helps make up for his lack of cantra, as professionals would call it. Even Gai fears Lee in his drunken state, so he must be really strong.

Funny thing is that we haven't seen anything ninjutsu or genjutsu based from Kimimaro yet. He's just pulled bones out of his body, but that's more taijutsu based than the other two. Maybe Kimimaro also leans more towards taijutsu. In that case it would be a very good match between them.