I just did this on my 2010 MPB and it made a HUGE difference along with cleaning out the dust that you don't see by just removing the lid. The factory paste job was absolutely terrible and I had a good piece of dust/hair stuck between the fan and heatsink. Before I was idling around 130-140*F, typing this I'm sitting at 105*F. I can't even get the fan to go above idle even under high CPU load.
Yeah i am surprised how high the temps go, I'm confident that with a proper paste and application they will improve. Awesome to hear you good results