The point with the standalone is that ITBs require a good old-fashioned cable controlled throttle, but the stock ECU relies on fly-by-wire throttle and gets massivley confused if you change that. Even if you added an airbox to use the stock MAF (makes the ITBs sort of pointless surely?) the cable control issue remains. It may be possible to somehow piggy-back the stock ECU but every Jenvey build I've seen (admittedly only three) has used a standalone for simplicity and enhanced tunability.
Totally with you on the HR though. You wouldn't need to do anything to the intake or internals on an HR, just cams and you'd have a pretty sweet N/A motor. It would cost soooo much more to make a DE produce the same power N/A as an HR with cams. For some reason that doesn't stop me wanting to do it though
DB
Hence how I've got 325-330 bhp by just changing exhaust, adding HFCs and changing panel filters to cosworth panels.
So much easier. ~ 54-59 bhp extra than a standard de engine. That's a small car!