water isn't the only issue in the shower... cleaning and mildew are also factors. also, if it were to crack/fail, you want to be able to remove the stuff and regrout/caulk.
not too sure how caulk would hold-up to cleaners. Would soap scum come off? Also don't know how easily mildew would grow on it vs standard grout... finally, not too sure how to remove it if it were cracked?
You mentioned you already had a corner of your shower done that way.... if you know the answers to those questions, it would help your decision.....
hey, if a company in the 80's made silicone / tile sheets, it can't be too bad, right? On the flipside, maybe there is a minor problem with them, and that's why it was discontinued?
sorry, I'm no help, as you can see :no: