I was there, it wasn't a user or installation problem.
He either got a bum unit or that was one of those air frames it just won't work well with.

I had excellent luck with my IGyro and it does some things I like better than the Cortex but that has to do with setup not how it handles, same thing, Cortex has some advantages but again, about setup, not flying. In practice they both work really well.

Personally, I think he got a bad unit but at the end of the day his jet was flying like it was on rails, something that I never saw with the other two units. Granted I've seen that particular jet fly a lot, but it was a visible difference even to an observer.