I've played extensively on 3/4", 1", and 2" slate tables. 1 inch is the most common. There aren't too many tables except antiques that have more than 1". Exception would be from Connelly. They offer their "Ultimate" versions in 2 inch. There could be others. I feel that the heavier the table is, the more stable, but speed isn't really a variable here other things being the same (cushion type, cloth weight/type, quality of the cloth installation, how tight the rails are held to the slate (bolts per rail). When you play on "thinner" slates, you might hear more of a difference than anything else. Ball-bounces will make the slate sound hollow. Thicker slate sounds more dense because it is and provides an overall higher quality feel, but that's all subjective.