My company has been at the forefront of developing a instrument training program using the PC advanced training device. I was one of the first accelerated instrument training specialty companies to train instrument pilots in the country using the PCATD.
I have a high regard for the PCATD and what it can do to expedite the training for my clients. I make it very clear on the first day of training that the PC hardware and software are not designed to actually feel like flying an aircraft. The intent of the "P-CAT" is to show certain tasks on the ground to the prospective instrument pilot that can be demonstrated in a more relaxed environment.
I have had experience with training pilots on all simulators, including the ATC-610 desktops. I honestly feel that the OnTop PCATD model excels in cutting down on the time needed in the aircraft to practice holding patterns, full instrument approaches, DME arcs and other instrument flying tasks.
The OnTop PCATD can only be used to log time for the initial instrument rating. It is approved for 10 of the 40 minimum required if used in a syllabus in the presence of a instrument flight instructor.