I remember some of the earliest mice in Sun SPARCstations, which in 1989 already used an optical sensor but required a metal pad with optical markings etched into it to work. While the precision and speed was much better than the mechanical mice of the day (much less effort cleaning them, too), I quite remember being constantly irked by the metal's higher level of thermal conductivity: the right palm of my hand always felt a bit cold and that might have permanently biased me against anything pad underneath my mice.
Since then I've preferred to go padless on a XXL wooden table I built and painted myself at the time, whose surface I actually expected having to repaint periodically, but it's held up just fine so far. And in terms of thermal conductivity and touch comfort wood is very hard to beat.
But I do notice that my gaming kids all seem to use pads on their wooden tables, so I guess in a professionally competitive environment you need to trade comfort for precision and speed.
Ah and yes, with ceramic tiles on the floor, I'd hate indistructible pads and tiles have go at each other: either winner would have me loose something...