My Half Arabian is quite mutton-withered and built downhill. The only thing that I have consistently found to help with saddle slippage (particularly riding down hills) is a Thinline pad.
I had a near-death experience riding down a bluff at Fort Robinson, NE–let’s just say that between my fear of heights, the narrowness of the trail, the SHARP dropoff with nothing but a few stumps between me and the bottom of the ravine, and my saddle heading towards my horse’s ears (and thus making him VERY cranky), I was totally and completely terrified. I was shaking when I got to the bottom.
After that, I bought a Thinline pad. Since then, I bought a second one so that I have a square one for my western saddle and a more shaped one for my hunt saddle.
They are not pebbly, they are smooth; and help with both side-to-side slippage and front-to-back.
I have tried NUMEROUS pads that were allegedly non-slip, and the Thinlines work the best for me–hands down, far and away the best.
I use them right next to the horse–NOT sandwiched between the saddle and another pad. They are “open cell” technology, which is supposed to allow the skin to breath better than closed cell. I usually use a thin pad in between the Thinline pad and the saddle, too (a navajo pad for western, and sheepskin half-pad for my hunt saddle).
I can now mount from the ground when I have to get off my horse while I’m out foxhunting, without pulling the saddle down underneath him!
If you let them get dirty, they don’t work as well, so make sure that you keep it clean. A simple wipe-down with a wet rag will do the trick.
In terms of “ripping the hair out”…well, I don’t find that it pulls any more hair out than most other pads. And my horse is MUCH crankier when I’m riding between his ears than when he loses a few hairs on his back. 