By far, the best hardware control interface is the OB (SEM), by saving mouse clicks and keystrokes. Just changing two parameters involves 7 mouse clicks on the ModMoog, 8 on the ARP, and only 4 on the OB. Please implement the OB control interface into your other V synths.
I was just double-checking these stats when my ARP froze from the 2.5 update. I'll have to reinstall version 2.0. (Mac OS X Lion)
The BEST suggestion came from Japan, I think, but I don't remember his name:
it would be amazing if there was a toggle option to turn on/off an info translucent layer over the synth's controls, pointing out at least which of them are mapped... or even better, showing some sort of user made label at the time of map creation, to easily and quickly understand, graphically, what's mapped to what.
I can't imagine how you would cover all the controllers out there, but if you start with your own (say, AnalLab 61), I would buy another Arturia controller keyboard just for this feature.