by putting a pivot shim between a piston valve and the first shim of the shim stack, does this give a plush initial feel with no effect to the rest of the travel?
It will give a plush feel but it will make a differnce to the feel on the track, you are bypassing the shim stack somewhat with this mod, and so it will not delfect much and this will make a difference to damping on all speed ranges.
Basically you should get a plusher feel but its likely to bottom more.