Zum...I agree with you about racquet power. A heavy racquet is harder to swing fast, so you reach a point where the power diminishes because you can't maintain your swing speed. That's why all baseball players don't use 36 oz bats. They can get more bat speed with a 33 oz. and therefore more power.
I played some more today with my London and had really good results. I tried really relaxing my arm and letting the racquet drop and my wrist stay laid back and the results where less balls sailing long. If I do everything right, the topspin the London generates always pulls the ball back down into the court. You can hit with a nice pace with a relaxed medium swing. If you muscle the ball and catch it too flat, it might sail on you. I think now, I just need to find the right string combination that lets the London do it's thing.