A flight director is not necessarily dependent or locked to an AP. In my experience, I would describe it more as dependent on flight guidance input, whether that is a selected altitude, heading, course (VOR, GPS, LOC), vertical path (GS or vert speed). The steering commands are based upon the guidance selected, with the intention of meeting that "defined parameter.
You dial in a new altitude, and the FD directs the pitch change necessary to get there, level off, then hold level flight. Has nothing to do with whether the AP is on or even installed.
I see it more as an intermediate step between flying around on raw data and fully coupled flight on an autopilot. In fact, that is the way I/we use it everyday at my airline...until the autopilot is engaged. Then the FD is irrelevant, since it simply mimics or displays what the AP is doing. From an engineering standpoint, it may be true that to get to the point of having a FD an AP must be present. But from an end user point of view--not theoretical, in the development lab scenarios--they simply aren't co-dependent
HITS is not the end all-be all solution to instrument flying. IMO, it fosters a lack of proficiency in raw data instrument flight and reduces the whole thing to a video game (and I'm not some WWII vet, good old days, "walked uphill both ways to flight school in the snow" kind of guy...I even have an Xbox 360 and no kids!) I will say, I found your display better/more comfortable than the "concentric boxes" I've seen--and been put to sleep by.
I'm sure standing in that booth and getting pounded with "but I want this" inputs for a whole week must get real old, real fast. Maybe I didn't ask the correct questions at OSH, but I too know what a FD is, I promise.
Joe