Oceangirl67, if you look at BlueStar's catalog you will find four different back trims, one for island and three different heights for wall applications. So it's an option in that you choose which one you need. That particular brand, though, has very high powered burners and they also say you shouldn't use a rear exhaust vent with it. On brands where you can use a rear vent, the trim kit might not be required at all in that application; the vent itself might provide the stainless surface to protect whatever is behind it. It's something you need to ask about for the particular range you are looking at.

I'm not sure if this is really answering your question but at least it should bump your post back up and maybe someone else will have a better answer.

The island trim I have has the vents angled forward. So it has not been an issue.

I have island trim on my bluestar 36" RNB. The backsplash is granite which covers several inches behind the stove also. The vent goes straight up. You can feel the heat when you are baking.

There has been no discoloration or damage to the granite backsplash other than food/grease splatter that we just wipe up.

I have the island trim on my BlueStar RNB. I bought a stainless steel backsplash online, because my backsplash is a light limestone and I didn't want it discolored.

I like the way the backsplash looks with the stainless range and the stainless hood :-) The stainless is also very easy to clean. Ours gets splattered a lot because DH is addicted to turkey bacon. I probably could have used some of our granite, and it would have been beautiful, but I'm happy with the stainless.