In early 2003 I got Monaco Optix at a camera seminar and used it and it was a nightmare - never calibrated correctly with lots of attempts from me. I think the software just never got it right.
Since then I stayed away from color calibration with my Apple Cinema display which is pretty good quality so I just got by with using canned monitor Adobe 1998 profile. I just didn't want to go through another nightmare with the complex and terrible profiling of the Monaco I had.
A couple of weeks ago I got the Pantone Huey Pro. It is magnificent. Easy to use - calibrated all our dispalys and my laptop. There wasn't a huge, huge difference as our Apple displays were in the ballpark but it did remove an awful greenish tint off all the screens and made the colors look richer.
The Huey Pro is small and simple, probably too simple for some but not for me. Again the more complex Monaco was a nightmare and the Pantone Huey Pro is not. My prints are very close to my screen image now, the only reason they don't match exactly is that my Epson is capable of printing colors my display cannot duplicate (e.g. many cyans). I understand the Huey Pro uses some of the Gretag technology and I also love the feature that is adjusts for ambient light as there can be some undesirable ambient light in my space here at times and the Huey Pro does a great job - plugged in all the time - adjusting for the changing ambient light.
Some might want a more sophisticated system but the Huey Pro is great cause it is very small, portable, simple and it works!
Best, Carol