You got a 1GHz overclock with a 640 at 45C load?!?!?! Thats insane!
But there is no way I would be lapping any of the heatsinks, I dont have the paper or guts to try that. But would the BT still be good non-lapped? It does look good.
I had the Big Typhoon as well, and from what I found, it cooled better than the 9500, but not as well as the tuniq tower.
So from personal experience, cooling wise it goes...
Tuniq Tower 120 > Big Typhoon > Zalman 9500.
All 3 of mine were un-lapped.
I kept them all on relatively the same noise level too.
I'd get the tuniq tower 120 if I were you. It's silent and a great cooler. The only drawback is thats its big, and doesn't look as cool as the zalman 9500.