Join Date: Oct 2011
Location: Illinois www.saddleonline.com
My first worry would be saddle fit, generally pad slippage stems from an ill-fitting saddle. (the fact that it doesn't slip with one saddle but does with the other makes me wonder if it is a fit issue vs a material issue). If you are sure the saddle fits well, you can always try a no slip pad, or even a no slip liner for the slippy pad if you are determined to use it. A thicker pad with more give might also help the saddle fit right and the help the pad stay in place.
Best of Luck!
"Riding: the art of keeping the horse between you and the ground."