I have a wa and my buddy just got a wee.
it does sag but you can prevent that with preperation. just fill it up at home right away with everything you plan on carrying and then weight it. if it's too heavy in the back, use a thick magazine as a plate replacement for some extra weight, vice verca. and then just tighten it up the right amount with it all full. it should help to keep it sitting nicely.
the quality is amazing with the HSGI stuff. I had a BHI vest for a bit and it wasn't even close.