I hope that GN team won't be angry at me if I share info that I've been given...
Herec is a quotation from email that I've received :
I wanted to give you a bit more info about future systems we have several new fixture coming in 2016. Our commercial horticulture range uses higher output/more efficiency LED's than the rebels and we have 150w, 250w and 400w models coming out in 2016. The cost again is alot lower per watt than the holographic series one and the spread light and intensity is much more uniform than the modular series (standard or with rebel upgrades). Actually the 150w version is very similar in shape to a Modular 6 however it has the added benefits
that its is silent cooled,
higher quality IP65 rated mechanical build,
much more efficient and reliable LEDs and drivers
More homogeneous spread of light intensity and spectra (this is really important for bringing out and preserving the natural quality of a plant and is one of the best features of the HS1)
Much lower cost that a full rebel modular 6 upgrade