I use Unitrack for my temporary and mock-up layouts.
It's great stuff. Flawless reliability, doesn't warp like other brands, higher quality rail, always in guage, excellent electrical continuity, the list goes on....
But.... Unitrack on plywood is definitely loud. I find it distracting when I can't even hear the radio over the sound of a Kato and quiet cars running. I have played with weather stripping, cork, and a few other insulators under the track. It makes a HUGE difference. I would definitely go with some kind of sound insulation if this is your permanent track choice.
1 3/4" sticky-backed weather stripping was my personal favorite.... but, I also had about 200' of it left over from hurricane preparations. It's a bit tricky to lay down, but deadend the sound enough to be worth it.