Decelerator... I've installed both on many customers' rifles. The most favorable feedback has been on the decel...
Only thing you have to watch out for is the metal plate inside. You MUST obtain the correct pad to start with or the installer may grind through to the plate and ruin the pad...
Of the two, the decel. is the easiest to install also... It does not require lubrication to grind down to fit. The mess created by the LS is a nightmare to clean up...
I agree with Redneck, but I can perhaps add one thing...
You can remove the steel backing plate from Pachymayr (sp?) pads and I've done so when gluing one on to a lightweight synthetic stock -- the owner wanted to keep it light!
Just fire up the belt sander, then start sanding on the back of the pad until you reach the steel (the sparks will let you know when you are there!).
Grab the steel plate with some dykes, then rip it out.
Sand the back of the (now thinner) pad until it is flat.
Epoxy on to your synthetic stock, shape as usual, and you are good to go, and have saved a bit of weight.
I forget how much the steel plate weighed, but I do recall that it was more than I expected. Still, this only worthwhile if you are really trying to save ounces!
I don't think this would work for pads that are not glued on though -- the steel is there to keep the pad from warping with temperature changes (or so I have been told -- seems possible anyway).
John