I might have misunderstood the DNA40 concept, but I thought it was more a VW with a setting for the maximum temperature you allow. Whereas VIR is purely a variable temperature. If I'm correct, with DNA40, you could set a max temperature that would never be reached by your coil (therefore it would not a pure temperature controled device, but more of a temperature "aware" device).
Anyway, it's not a major difference, and sadly it sounds like there's gonna be some patent war, I hope we consumers won't be impacted ...