[b]Fenian[/b], I ended up getting a bag of them today from the Oly store. I guess the proper terminology for them is "Lo-profile covers." Anyway, I do foresee them getting quite hot. My impression is that they are actually intended to protect the rails from damage, possibly (instead of the rails being exposed to bumps and such). Regardless, I'll probably wind up putting a guerilla grip on the forend anyway. BTW, since my stock is wrapped with 550-cord, I opted for the OD green covers. It looks kinda cool with the way they contrast against the black metal.
Also, I tried some KAC panels from work and they do work pretty good, they just leave quite a bit exposed at the very ends. All I had to do is mash them down onto the rail, making sure that the metal clips were INSIDE the the rail rather than outside of it.