I run single ply on the front and dual ply on the back, the dual ply is a big fat beast. I would agree, about 400g heavier. I've never had a single flat though, pinch or otherwise.
I think if you run tubeless prob OK with a singleply as long as you avoid those silly LUST things or the eXception that have the thin walls.
I'm going to stick to dual on the back of the hardtail as I am heavy and have little talent for riding smoothly. on my full sus I seem to get away with a lighter tyre on the back