DD- is the difference a certain lack of subtlety in the initiation of an inhalation? I have almost no experience but it seems that my Deep6 regs give me air more freely than I'm used to but if I'm just sipping my air, it isn't a terribly smooth transition from none to just a bit. I suspect that in a few dives I will get used to it and at that point the very low WOB will be all I notice. I also wonder if this is adjustable or is it perhaps the result of the little turbine inside spinning up? I'm going to go find the drawings I saw of the internals.