I recently became a team rider with Hot and yesterday received 4 of my sails, today it was windy so I got to use one and have written about how I found it.
www.redsurfbus.com/2012/01/hot-sails-maui-grand-prix-speed-gps.html
Hope you enjoy reading it 
First thing is it works better with a wider boom, need to change my biggest boom for one with a wider back end.
I have ironed out the rigging/rotation error from the review I did - too much downhaul. They dont need as much as other race sails I have used, and still twist off very well. I think the triangular panels up the sail aid this a lot, meaning the leech does not have to be as floppy, which is nice when cranking upwind as it doesnt rattle and the whole sail works well when pointing high. I reckon I am getting 2 knots faster at the same angle upwind and able to point higher.
They have so much power, I am only a good intermediate so rough conditions I have never before hit in the 30's but have done nearly every session now (its springs here and portland harbour empties this time of year leaving your only choice to sail a good 400+m offshore, also there is a channel that floods out creating very confused chop).
I cannot wait to get them on the flatter water as I really think I will be a couple of knots quicker in the same conditions. I am now convinced that I will get my PB max (currently 35.45) in much less wind with these sails.
I am trying to put into words the difference in feel, but not rushing to get it online until I am happy with the explanation, had a few more sessions on them though, used the 7.3 from 12 to 30knots and it handled it very well, was caught in a sqaull gusting to 50knots today and still managed to get back to shore (just!!!! and it hurt a lot, thought my arms were going to explode)
If you are into speed/distance/endurance/slalom then please try one of these sails!
I've been using a GPS 7.3m Demo sail (Thanks HSM Aust). What I liked straight away (using the reccommended skinny) was the sails ability to absorb shocks and jolts in chop while still responding to gusts with increased speed. The other thing I noticed straight away is the sail was relatively heavy, not heavy in the hands in use, but the actual dead weight. Looking at the construction gives you a clue as to the weight, it's very solidy built (sherman tank like), lots of reinforcing and a very robust looking luff sleeve.
Unfortunately i haven't had a chance to do a GPS test on the GPS but I'm confident I'd be faster in rough water as the sail would be less taxing on the body and easier to push to the limit.
It has good power and when I rig it with my NP mast it has even more power, however it feels stiffer. Yes, the profile certainly feels the boom, lot of shape at and below the boom and flattens out nicely above the boom.
I actually find the rotation is pretty good for a race sail. The bottom cam sometimes sticks a little but I suspect that as the sail stretches and a bit of fine tuning it should be fine.
All I'd like now is some wind so I can really put it through it's paces.
I had a first outing today on the 8M HSM GPS with the reccommended skinny mast.
Wind started 8-12 knots ENE and with a few gusts up to 18 knots.
Rigged the sail and immediately noticed it had big profile, heaps of belly under the boom. With neutral OH it virtually followed the profile of the boom. (comparing to my NP RSS 111) with the similar settings the RSS just touched the boom towards the back half). Pick below of GPS with an NP mast with more than recomended DH.
The sail has power. Using an Exo RS5 with a tectonics 46cm CR Fin, I could pump it on to the plane it what seemend to be no wind (maybe why I was the only one out)- around 10-12knots. With the big fin I could charge upwind even lightly powered. With the bigger gusts up to 18 knots it was totaly unfased and sailing was very relaxed. The sail was soft and breathable (felt like a wave sail with cams) and rotation was efortless. The soft feeling of this sail made the the ride though chop very comfy. However it did lose a little in directness compared to the RSS. Whith a gust the RSS would immediately charge you forward whereas the GPS was a little more slingshot like.
The other interesting difference between the HSM GPS and NP RSS is that the boom and mast setting on the GPS is about 10 cm longer, but there is only a .2m difference in size. The sail didn't feel cumbersome with the extra boom lenght..but I may need to buy a longer van!
Speaking of GPS the combo managed a respectable 28knots in what was quite light wind. Love the efficeincy of modern gear.
Looking forward to giving the sail a workout in the top end of its range, will we ever see 20+ knots in Sydney again. 
Hi Des, are you using the HSM 460cm mast with it?
I wouldn't mind trying out the GPS after demoing the Speed Demon which I really liked. However I'm afraid after trying it I'd want to buy it........
I felt a similar smooth feeling with the Speed Demon over chop. It was very comfortable and felt like I could sail all day without much effort with it.
You should post your times up on the Challenge site so we can see how the sail is performing.
Had my 4th session on them yesterday, and paying for it today......its amazing how much fitness is lost after 3 weeks of hibernation.
Went out on the 7.3Hot sails GPS with a 35cm Type R black project fin and later the 32cm Type S.
Only tried one nautical mile run and beat my PB by over a knot, its not high (26.96knots) but good for me in a location where the nmi is a difficult run with several different water states over the near 2km. I seem to be able to keep the power on for longer through rough water, always in the past I would get a good start for the nmi and then start to lose control or power about half way, ending up with the first half at about 28knots and the second at about 22knots. Looking at my track I can see that I was able to keep the power on for much longer.
My friend took it out and got 37knots from it 
, so I now have a target to attempt otherwise the sail will never go so fast again apart from in the back of my van....my best ever is only 35.5 so its a pretty big target for me.
Done a bit more detail about my first few sessions on the kit. There is no wind over here in the UK at the moment, its really frustrating as the air temps are quite good and the water isnt too cold either. It is a lot warmer than this time last year, I am hoping that this will be my first summer when I can wear shorts and a rashie for a few sessions.
www.redsurfbus.com/2012/02/hot-sails-gps-developing-feel-for-sails.html
Hope you enjoy the read
I had another session on the 8M gps today. This time I used the max reccommended DH & OH, which in retrospect was a tad too much down haul. I was expecting a solid wind but as it turned out it was flukey more like 10-20knots.
The sail did feel a little more more balanced, less pull up top but it did lose a bit of power. I used my Tectonics Talon 42 cm but it felt a little overpowered with the extra grunt this sail has. Good across and downwind, but going a bit sideways trying drive up wind. Got one good downwind run and managed 30.7knots (2 sec) on the dial - still a couple of knots short of my big sail PB.
I did get a couple of 20+ knot gusts and the sail felt solid and manageable. The standout feature was how smooth it was in the gybe, no pull and snap, it rotated so smoothly, not much difference to my camless sails.
So my optimal setting will be about 1cm less DH and I'll start trying out the higher clew positions (using bottom one so far). I'd just like a solid 15-25 knot day to test the upper limits - fingers crossed for tommorow.
