Crank Length?

anyone notice a difference between using 170/ 165? Do you feel like you've got less leverage on 165's? Or that your legs are spinning more? I'm looking to replace my set which is 170.. thinking about 165's...but I'm afraid. very afraid.

I reckon you can tell the difference at the extremes of your cadence.
165s allow me to achieve a slightly higher cadence, which I like for fixed.
175s allow slightly more leverage, which I like for offroad.

(My commuter has 170s which seem to be my correct length for a geared bike)