I switched to slate because I was worried about impaction--you won't have to worry about that with the tile. Also, it is very easy to clean. I'm not sure about the heat transfer because it depends on what kind of heat source you're using and I'm not sure how to compare it to heat transfer with other substrates. Personally, as long as you regulate the temps, tile is what I recommend.
I switched to ceramic tile after a problem with impaction. Easy to clean, I just pull them out and rinse them in really hot water and then lay them back in.... I have them laying over about a quarter inch of sand, this works out perfect for the heat with the UTH, if it gets too warm in the summer, I turn the dimmer down, I have the UTH on a dimmer switch....
Yes, it transfers very nicely.
I have a temp cage laying on top of it so I can keep an eye on how warm it gets, if it gets close to 90, I turn down the dimmer to reduce some of the heat...