I've had my beardie on tile for about 6 months now, and she's loved it.
I personally have loved it because it's made cleaning up much easier - because when a beardie has to go - my god can they go! Also, Lazlo has a tendancy of walking through her food and getting it everywhere. I tried different substrates before - bark, all towels, sand - and nothing worked. So, at least for me, tile has been great.
I do, however, have her hide over a washcloth - that seperates the heated tile from her skin - so she doesn't get any direct heat from underneath. Also, I took to placing a hand towel, folded up in her cage - it makes a little pillow of sorts. It's hard to get her to move from that.
I would recommend tile - especially if you are already using it with your geckos and have had good experience with it. My geckos also love the tile....
- D
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2.0 Dogs (Dante the 110 lb. drooling lab & Amos the mutt)
0.1 Bearded Dragon (Lazlo - the pickiest lizard every met)
1.4 Leopard Geckos (Randall, Dagny, Kira, Dominique and Ayn)
1.0 Husband (the most obnoxious and yet rewarding pet of all!) 
dacia2002@yahoo.com