Short HDS history as I recall what I can remember:
In the pre-Luxeon era, 5mm white LEDs ruled the white LED flashlight market.
HDS Systems (which are the initials of the creator, Henry D. Schneiker) made a light for himself and a few friends called the action light. It had an array of 24 5mm LED emitters. Reliability and durability were of utmost importance, because the action light was made for caving.
Then Arc Flashlight LLC appeared on the scene with the first Luxeon flashlight on the market, the Arc LS.
It is my understanding that Arc approached HDS and hired his services to develop what would become the Arc 4 light, which was descended from the Arc LS and subsequent models.
The HDS and Arc's creator (Peter Gransee) both are listed as inventors on a patent for a power supply (patent #20050151518).
However, there was a falling out at Arc Flashlight (I believe a non-disclosure agreement was violated) HDS Systems then created the EDC series of flashlights, which picked up where the Arc 4 let off, and the flashlight world has been better off ever since.
Then Novatac entered the scene. Don't know anything about them, other than they merged at one time with HDS. Henry posted recently that HDS Systems was back in business, but no details have emerged.
I placed a pre-order for the EDC 85P, because I find my HDS B42 to be bright enough, so an 85 should keep me happy. If money was no object, I suppose I would have pre-ordered the 120, but I think I'll be happy to get the 85 and save $40. If they are like the HDS lights then they are both bargains.
I welcome any comments or corrections about my HDS history.