Are the glass ones transparent? If so you can possibly run into the water collecting behind the tile which could lead to mold growth that you could see through the tile. Just make sure they get sealed properly and you wont have a problem.
The stainless steel tiles are badass. I put some in my kitchen for a backsplash. What size are you thinkin of buying? If you go too big...they might get a little slippery. Only other problem you could have is, if you have hard water, they will get a little cloudy.
They make every size ass look cute. They are instant girly-girl and edgy at the same time. They strrrrretch, so one size really does fit most. Best of all, they are a great conversation starter, people always tell me how much they love my ruffled panties with the little bows...
This is awesome news because I just got a TON of ruffled undies from my girlfriend. She says watching my hairy ass hang out of some Victoria's Secret purple angel panties just turns her on like a brand new Ford Mondeo revving on the interstate.
As long as the tile isn't absorbant it will be fine. Glass obviously won't absorb water, so that is fine. I don't know what the SS knockoff that you are talking about is, so you would have to ask the tile distributor.
Be sure to use a tile backer that is approved for wet areas. You'll also need to seal the grout lines with multiple coats, and then reseal every year or so. Using a tile that will absorb even small amounts of water and putting sealant on it is not a good idea. Also be sure to use siliconized caulking around all of the corners/edges.
Does your bathroom have a window? If so, you should really consider what kind of window treatments are available to match to your tile selection. Also, you have to consider your overall bath theme, for instance, if you're thinking about a Louis XIV vanity, which can be quite fabulous, the stainless tile will be truly gauche and you should think more about...
WTF??? I think I'm turning into a gay TLC designer, nttawwt.