Yes, but theyre not very similar; much more friction than I like. There's the Razer Scarab (good, not great) and Ironclad (plain bad--and very pricey :/ ), for the record.
Roccat has a pretty good aluminum pad, but my g9x experiences "dead zones", ostensibly due to the frivolous graphics. Saitek just came out with a smaller aluminum pad which has an almost identical glide, and I'm considering switching to that. Still, it's too slippery and lacks the smooth yet somehow steady glide of the SX.
I think what makes the SX special is the coating and micro-texturing (extremely subtle--"brushed"), which nobody seems able to emulate.