“I have a hard time imagining how an incomplete bevel set can lead to a "collapsing edge."
The edge is not collapsing, it was never completely sharp and the user was shaving with the part that was, then they think it stopped shaving when they shave with the part that never was.
This is the result of the Pro Forma, (X amount of laps) honing. You have to hone as long as it takes, to achieve the results you are after.
The OP probably spent much more time on the GD, (because of its reputation), that he is comparing to. It would be interesting to see the edge of the GD.