I don't have any first hand experience with the Helicomatics, but Sheldon Browns states:
Originally Posted by Sheldon Brown
Both hub flanges were 1mm farther to the left than those of a normal hub, causing increased dish in the rear wheel, and persistent spoke breakage problems. Many loyal Helicomatic fans tout the ease with which the cassette may be removed for spoke replacement as a great virtue, but if the hub were better designed, it wouldn't break so many spokes!
These hubs were prone to bearing problems as well. Due to clearance requirements, they couldn't fit the normal 9 1/4" bearing balls, so they used 13 5/32" balls on the right side. These didn't hold up well. The cones tended to wear rapidly, and replacement cones are no longer available to fit these hubs.
I usually listen when he speaks.