I've been using them for a bout 3 years. No issues, but the sizing is sometimes a litte off on older sizes. I am wearing a 36 and they are a little big on me (my waist is a 35-36). I think the newer sizes run a little smaller, so be sure to ask when you order them.

On the larger sizes, use the large spreader bar... on the smaller sizes, the medium spreader bar. A spreader bar pad is a good idea so the bar doesn't dig into your hips. Also, ride with the bar a little loose so it doesn't twist into your hips, but not loose enough to disconnect on one side if you ride toe side. There is a small screw which locks the bar into one clip... make sure that screw is on your left side if you ride left foot forward most of the time.

Also, there is a hidden buckle under your rear end hidden inside the shorts... tighten that up so they don't ride up on you.

I love mine.. It doesn't even feel like I am wearing a harness and no back pain. Plus I can't forget it and leave it at the beach and it's one less thing to carry when walking out. The hook is lower, right at your center of gravity, and you can edge harder and pop harder because you are using your legs instead of your back. At first it'll feel weird because the pull is so much lower... give it a couple of sessions to get used to them. They make the huge bar throw on modern kites easier to deal with too...

One more important thing, buy a pair of "Under Armour" from the sporting good store.. you know the lycra sports underwear. This will prevent chaffe from the straps so you don't end the day with a huge rash. With those you will never get torn up down there. I recommend them for surfing too... no rash between the legs from walking back up wind.