Sherman, set the way-back to 1986
Sherman, set the Wayback to 1986.
Right away, Mr Peabody...
I bought an '84 620 new in the fall '85, and loved the Helicomatic hub for about 300 miles. Then it was spring, and I started riding it in earnest.
It was beautiful to look at, and great fun to remove from the rear wheel just to look at the splines neatly machined into the hub. The tool had a bottle opener & spoke wrenches embedded in it (I still have the tool).
My real issue wasn't with broken spokes, but with my inability to find a chain that wouldn't try to find a happy place in between sprockets during higher than average torque events. I often toured somewhat aggressively then, and the blasted thing would autoshift at the drop of a challenge. And just forget trying to shift under stress. I suspect the hills of western PA & NY are still echoing my curses of this particular bit of Gallic engineering. Sedisport, Regina, Ultra-6, Ultra-7... I must have tried 3-4 different chains... Some of the onus might be on the Duopar derailleur, but either way ... ick. Eventually I figured out how to mostly ride around it's limitations, but it was only by having the stupid hub cut out and replaced by a very pedestrian Suntour 6 spd that the problem went away. It's been 20 years since I rode with that hub; I haven't missed it one day. I think I even gave it (& a spare freewheel) to the LBS just so I wouldn't have to look at it anymore.
I'm sure someone has had a happy experience with it, and maybe if you rode it at 10-12mph on sunny days and never pushed it very hard it would be a fine thing. I didn't; it wasn't, certainly not by comparison to what else was available at the time.