Problems w/ diablo gear changes if you do them yourself. I can't do it w/ my programmer and found a thread on mod fords where everyone else is having same problems. Called Diablo, they did not deny it, they just offered to correct tune via email. I also heard the flasher is faster w/ the new SCT.
If you are going to do your own adjustments I would think SCT might be better. If you are going to have someone else make up the tunes for your car then just find a good Tuner.
Local Diablosport ~ Larry @ Speed
Local SCT ~ KurganMotorsports @ Speed, Randy/Doug @ Sutton
Mail Order Diablosport ~ James @ RWTD
And there are many more.