I'm in the same boat and wanna know the same thing. Apart the weight drop would there be any gains due to less drag from the crank not having to spin the pulley??
I was thinking of this too, I let the gas out mine last summer and apparently leaving the system empty destroys the seals and renders it useless? I have climate control though, does anyone know if anything dodgy will happen if I take that out and whack in one of the twisty knob units?