Had a play on one one of these this weekend in some light conditions and was quite impressed with the performance.
First impressions.
The sail rigged easily, the cams popped on without any fuss, the rigging video on the NP site was spot on for how to do it (would recommend watching rigging vid's for any sail).
Rigged the sail on a 460 X6 (can also be rigged on a 490 X6)
The sail is designed primarily for bottom end and getting going in minimal wind and looks quite strange compared to my normal sails by having a tighter leach, there is still twist of but it is greatly reduced, the bottom half of the sail has quite a nice shape to it.
On the water the sail does not feel 8.5m, I've got smaller sails which feel heavier than this. It was quite a noticeable thing
We had 8-15knots of wind with the breeze mainly in the 10-12knot range.
Give it a hint of hint of wind and it gets going, it's not going to perform miracles but it does feel like it gets going easy, when the wind picks up the sail doesn't feel top heavy with the tighter leach (one thing I was expecting).
The 2 cams are the Ultracam's as used on the NP race and slalom sails rotate without any effort.
From my first play I'm well impressed, the sail delivers what they promised, is easy to use, will be ideal for the sailor who wants a cammed sail for light winds but doesn't want a race sail.
NP Web Pagewww.neilpryde.com/sails-2009/flatwater-sails/v8-helium.html
Review from Boardseeker Maghttp://www.boardseekermag.com/equipment_reviews/equipment/Neilpryde-Helium-075.htm
I had the opportunity to test a 8.5m Helium (with my 90kg) on a Isonic 111. The first thing I noticed is that the sail felt really light, both maneuvering on the beach and on the water. I'm still getting used to my new Isonic so my planing technique needs work. However after a bit of practice I was planing in 8-12 knots, even at times with chunks of weed hanging of my fin. In really light stuff (i'm talking puffs) I could get the board to drive of the fin by hanging my weight of the boom and chug along in a semi planing state.
I only had about 20 mins on the sail before the wind died completely so I didn't get comfortable with locking the sail down to the deck, also a bigger fin would have been useful.
So if you are after a light air sail that is light to use then the helium delivers the goods. 
