Have you tried a simple innertube piece? I've used them for years - ugly, but works better than any slip on.
I used to put rubber Decal Grips on an HK USPc for a while... the inside panel would always end up peeling off with IWB carry. SO, while tempted to try this new grip for the Shield - I don't want to have to worry about that happening again...
I got tired of buying sets over and over and replacing just the 1 side...