Meet a couple Guys with the ION Shorts (knock off of the Nitrous) and they seemed to like them.

I've got a Fusion Harness and also have a North Styler waist harness that works well.

If you like the Fusion harness and it works for you why not stick with it, as they say if it ain't broke don't fix it.

Though it is nice to have a waist and seat harness. Waist harness for mobility and when you get a bit buggered but still want to kite you can skip the can of HTFU and put the seat harness on and spend a couple more hours out there.

One thing to note is that if you wear a impact vest they don't all work with a waist harness is you want to go that route

I started with the Dakine Fusion and used it for the first season, they are a good harness but rather restrictive particularly for riding toeside, surfing, even when you have to do the walk back up the beach.
I tried a couple of mates waist harnesses (not sure what brand now) and didn't like them, they all seemed to ride up. I eventually got a Flying Objects harness from Airborne in Osborne park and love it, heap less restrictive and it doesn't ride up and bruise the ribs.
It still took a while to get used to after a season with the Dakine seat and as Liz said with the seat type you seem to be able to hold down more power in strong winds. If I have a couple of consecutive long sessions I still sometimes use my Fusion seat as I do seem to tire quicker and end up with a sore back if I use the waist for extended periods but hey I'm an old coj. Most of the time though (and always when using my surfboard) I use the Flying Objects as you just feel so much freer.
The Flying Objects has as well as the main spreader bar strap a smaller strap coming up from down low on each side to the spreader bar that stop them riding up.
Lots of guys seem to like the Mystic Warrior but I tried both on and the Flying Objects just felt heaps better,softer and more comfy on me, so definetly try a few on.

Hey Juddy,

I went from a Fusion, to a Pyro and then another Pyro (hated both of them and the Fusion), then went to a Flying Objects Flight Control and then upgraded with the newer model.

I've been riding the Flight Control for the last two seasons and it's still as good as the day I bought it. It's been comfy and reliable for two hard seasons and has good back support, so much so that when I do actually do my back in, I have worn the harness on the beach whilst teaching and it has supported my crook back so well I felt better for having worn it and was able to get through a day of teaching.

At $240, they are a great harness.

Good winds,

Go the Dakine Nitrous shorts, doesnt even feel like you are wearing a harness.