Mojo, does he need in-wall cable? ... if so it should be rated for that ...

It's a fire hazard thing which IMO really doesn't matter too much if the run is short and stays in-room but there could be problems if it was discovered.

Current plan in the HT is to run any possible on-wall bed surround (M5ow) with a short run to a connector just below it in the floors wiring channel. That way I can run the rest of the run using regular 12AWG. You can do the same thing just above the floor.

BTW haven't look yet but if 12AWG Class 2 is hard to find you can get smaller gauge and double it up... I have 4 wire Class 2 speaker wire which would work fine for this.