I think it partially depends on whether you want the backsplash to look "framed". That's essentially what the porcelain tile will do because it is visually different from the glass tile. Bullnose tends to be more expensive than field tiles, and you will (almost definitely) have some scraps left over from doing the shower. I would consider cutting some of those scraps into the strip shape (as you would the bullnose) and taping it up as a layout to see if you like that framed look. If you do, then go ahead and cut the bullnose and tape that up. This would hopefully save you some money if it turns out you do not like the look of the frame around the glass tile. My personal preference would be to not do the bullnose around the glass tile. To me the mosaic is very pretty and has a lovely rounded edge and I would not want anything to take away the focus from the glass tiles. However, this is just my opinion, so feel free to ignore it.

I agree... and disagree... with your sales person. I agree in that there's no need for crack isolation behind a backsplash. However, I DON'T agree that it's okay to install glass with any kind of mastic, no matter what color it is. To get the same ease of installation that your sales person's talking about, and still get the strength of thinset, look to the non-sag thinsets. My preference, because of how highly modified it is, would be Laticrete's 255. Most glass manufacturers recommend using their 254 Platinum thinset because of its bonding strength. The 255 not only is a non-sag thinset (it won't allow the tile to droop while drying like most thinsets), but it's also got even a stronger bonding strength than the 254. That's something not one of the other non-sag thinsets can claim.

Thank you! I'm leaning towards the garnet myself.. because I am too a red kinda gal, but was afraid it would be too loud if you know what I mean. I was thinking it would be more serene with the blue/green, however the granite has specks of garnet in it, which I think would look really nice. Its called bourbon blend and found it online. http://www.glasstilestore.com/bourbon-blend-p/bourbon%20blend.htm

Just came across this. Hope some how the answer gets to you. I did a mosaic back splash. Stained glass mounted to mirror backing in sizes from 6 by 13 to 9 by 13. Almost two years ago. So far no problems. We do have our house on a regular cement foundation. Good luck Here is a link that might be useful: Glass Back splash.