Bob, cages are interchangeable between Vx-GT and Cyclone-GT. You can't say that one has a spring failure problem, and the other doesn't.
I swapped a cage from a torn Vx-GT onto my Cyclone (short cage) about 12 months ago. The cage on Vx-GT was identical to the Cyclone-GT cage on several other derailleurs of mine, other than the labeling, which said "GT", not "Cyclone GT". I think that one of the main design changes in the VGT -> VxGT redesign was to use the ligher Cyclone cages.
- Don Gillies
San Diego, cA, USA