Do mats tend to sound like their material, meaning copper and carbon fibre would sound more lively than rubber?
I find that's pretty much true, but the Boston, Micro Seiki and TT Weights are all hard mats yet each offers substantially different performance.
My advice is go for some of mats suggested, but buy used here at Audiogon. After testing, sell off all but your favorite.
If you shop smart you may not even loose any money and you'll learn a lot.