A little bit of progress... we moved to a new studio in the fall, and all my prototype stuff was tucked away in the storage. Building up the studio took most (if not all) of my free time, so i didn't get to do much with Halsugrip stuff.
The good news is, there's now a dedicated service corner in the new studio, with much better resources for working on this stuff. And it's pretty much done now too. All the screws, nuts, bolts, aluminum profiles, custom parts, tools etc. have their own little homes, it's much more organized (or will be, when i get what's left of the chaos sorted out - that takes some serious effort i can tell you).
This said, i worked on the moco system last night, after a long break - what better to do in the New Year's Day than to tinker with the nerdy stuff, eh?
And lo and behold, i got pretty much all the remaining mechanical stuff done - even tried on a DSLR and found out that the head feels plenty sturdy enough. Next it's just a matter of putting the electronics together, and the "small" task of coding the control software for the moco.
As a side note, for now i built the base for the head using a narrower track width than in my original plans - this way it's compatible with my existing manual mini dolly gear. It's not pretty, i had to improvise a lot - but i will likely get back to the wide track later, that also helps to accommodate the on-board electronics and controls. For protoing the system this smaller, stripped-out Frankenstein version will do just fine.