actually, the cut and shortened setup I run now is about 3/8's of an inch shorter than stock and, as you mentioned, probably compresses more. I haven't checked the shocks, but after posting this I did beat the snot out of my X on a dirt field near here.
I also ran it across a couple of spots on the street which are known to get the rear to bottom badly. results: totally better- that shorter mount made it not slam anymore. previously the single cushion was only a little better, but could still be too harsh. I almost wonder it it has altered the timing of when the slapper pad on the front of the leaf reacts in time with the main bumpstop. I was saving the full uncut timbrens for after the lift, but unlifted, it seems quite fine short of jumping the truck. I know i got the ass end airborn with a full tank and a 150 lns in the back on my dirt field run. It's fine compared to stock- i was surprised it didn't slam given that the half stop solution before the mount shortening wasn't quite good enough.