We have a super-high quality Sterns and Foster and this nicely thin protector lets me feel the great mattress underneath. I don't want any extra padding. We haven't put waterproof, etc. to the test, but I'm hoping those are fine. It fits our super thick King mattress, no problem.
This mattress topper is a must have. I feel like I'm sleeping on a cloud every night. My mattress, Stearns and Foster, is very firm so the mattress topper creates some balances b/w the firmness of the mattress and some cushion. I love it.