"What about for an off the floor permanent layout'
I use both Tomalco and Shinohara code 100 and find them both excellent. I hand lay my turnouts with matching code 100 rail.
I don't have any S scale temporary track but I have some O scale Lionel fastrack which is similar to the SHS/ Lionel S tracks and I find it quite handy. I don't think sound will be an issue on a temporary layout set on carpet other than keeping the kids from blowing the horn and ringing the bell constantly :> ........DaveB