For a bathroom, I'm not sure how a slider will work for privacy or sound proofing. Really doesn't seem appropriate. If you go with a pocket door, don't cheap out. Get a solid door and a metal frame with a heavy duty track. Cheap wood pocket door frames warp, and that fix alone will cost five times what you "save" going cheap.

Keep in mind that base IRC code (if you are in the US) will only allow either of these if it is an ensuite bath, and they are not IRC compliant as egress doors for things like bedrooms.