I wasn't actually thinking mechanism.
I attached a model similar to what I was thinking. I put the balls in the part model just for now. Just about everything is driven through relations. It takes into account just about everything mentioned in this thread.
I did learn something. If you look at the way I created the "lead-out" for the helix cut, you will find a surface helix based on the master helix. You will also find a revolved surface that has the lead-out profile. When I intersect these two surfaces to generate a curve, it takes - f o r e v e r - to define a sweep along the resulting curve 
. I opted to trim the surface helix with the revolve surface to provide an edge instead. This was - m u c h - more efficient!... yet it failed when I modified the revolve surface...
so I then created the "intent chain" to drive the helix cut.
Attached is a full version Creo 2.0 part model.