Today was the test gusty wind choppy mixed up water 1st proper test of a waist harness on what I call a big sail 7.0 V8, and the winner for me is waist over seat. Might put the seat harness in the Sandy Point bag.
The only problem is seat wins the google fight 
I was thinking of trying that out too Jman.
Have only tried seat so far.
Whats the difference?
Any back pain?
Does it alter your style much? (this is probably a goog thing for me anyways!)
Do they move around much?
Any other pointers? Such as best harness makes and styles (the back bits seem different for each manufacturer)
Searched 'waist harness' and didn't find anything on those questions.
99% of speed and slalom sailors can't be wrong can they?
For blasting the lower purchase point plus being able to put your weight into it makes the seat the winner. For waves or playing around waist or chest harnesses are best. I haven't used a waist harness but I reckon with my body shape it would soon be around my chest and then crushing my ribs.
Google fight is rarely wrong too.
I tried a Dakine Pryde and Naish waist harness's over seas earlier this year as I only had a seat harness in AU. I have since spent stored the seat harness and splashed the cash and bought a Naish Elite waist harness. It is just fantastic!!!
I am no where near the level of skill or sailing as long as most of the people of the forums, however as a Joe Blow new to the sport (14months) rider trying to improve each session and it has been a massive step for me. Higher boom, heaps of comfort (the naish smashed the others for comfort), way way less catapults and just a more comfy feeling hooked in. I am really happy I tried it and took the step.
There is a recent Peter Hart article in the UK Windsurf magazine where he bags out the waist harness and basically blames it for the decline in windsurfing's popularity.
He basically says the waist harness is popular as its easier to use when getting used to harnesses as you don't feel so locked in, plus the higher hook makes it easier to hook into. The fact the seat harness looks like a nappy makes the waist harness more popular too.
However if you start using a waist harness for big sails then you run into problems as the the power cannot be controlled well with a waist harness that rises. Your stance is inefficient and you end up not going very well.
Many PWA sailors use both types of harnesses for racing - depending on the conditions - i have heard of racers going for the seat in flatter seas or lighter winds (for lift , drive and efficiency)- and then switching to a waist set up for choppy / windy stuff - the waist configuration allows better shock absorbtion through the legs.
Waist harnesses are much better for wave sailing where out of the harness freedom is super important (a seat harness is quite restrictive mid aerial move) - same for freestyle. Personally i find the waist much nicer in the top 60% of any rigs wind range.
And yes seat harnesses do look awful from a fashion perspective. Really awful..
However seats do give better low end crispness and lift in the light stuff - i think they actually allow the rider to go higher and hang longer in a standard hooked in jump too!
Seats can also cause back problems as you get direct shock loading straight through the spine - whereas waist harnesses tend to open up the vertebrea and spread the load over a much larger area. Waists also allow some rotation on the body to "autocentre " - very handy when going upwind - seats will tend to torque load your spine as they can rotate against your body.
Choose your discipline, conditions and sailing style and the choice should be fairly easy.
And if you cant - Flying Objects make a really nice waist / seat combo that gives the benefits of both types of harness.
google fight - pfft.
waists are great, also stops you sitting down on the job, and no straps digging into the jewels, go to a shop and try heaps on, their all different, some have heaps of support for your back, like the mystic waists and others like the da kine nexus are supper soft. if your running big sails the seat harness's are more necessary, than an option.
I sail from 7.5m race sails down to 4.5m waves sais all on a waist harness. Love it and wouldn't have anything else.
I use a kitesurfing waist as I found it was actually a little better for support than others I tried when I bought mine. It also has a few features that were yet to hit windsurfing harnesses like locking the hook in position. The handle on the back is handy for carrying it around as well 
I did my back in big time when I switched to a waist harness. I made the switch on the recommendation of an instructor at Mui Ne, and although it made some aspects of sailing easier (ie unhooking in sudden lulls), it killed my back.
Why? Becoz with every bit of chop I hit, there was this thing pushing into the middle of my spine, trying to bend it out of shape. After a long recovery period I started using a seat again and it was better. Lately I've been experimenting with the waist in lite winds but it's still BAD...it makes my back want to twist awkwardly, and it presses in the middle...and it's hot...
just my opinion...always trying to be different...
We are all individuals and have different backs. My lower back is a bit dodgy lately, getting old, however it always feels better after exercise including windsurfing. For me, the seat harnesses major plus is being able to sit back and relax when planing. Nothing beats that armchair ride when everything is so easy.
I have tried both extensively for Slalom and Formula. I am now trying a combined seat/waist harness to see if there is a happy medium. Failing that i will return to using my waist, as comfort is the most important thing.
PS: hooking in and out with a waist is so much easier.
i have a tattered nexus by dakine and several times i had the belt overlapped and stiched over since the bar is eating away on it..so time to upgrade..i went to the site of solent sailboards where they have a clearance sail and so is the 'the-house' and when looking at the nexus they don't show the front webbing and seems different now..so which of you think value for money is betterthermoform, nexus or t3..the 08' model says 'very low profile' and i really don't understand what they mean
