In US FAA training, hi-fi sim is used almost exclusively in Enroute training. The equipment, which cost a zillion bucks, is excellent in portraying "live" traffic simulation. Even veteran controllers work up a lather in some of the busy scenarios. The question, of course: is this the best way to teach?
As Mr. Pig notes,
...high levels of physical realism in simulation do not guarantee effective transfer of training, and in some cases are even an obstacle to it (too much extraneous information).
In early training scenarios, students are learning fundamental skills. Instructors need to step in often to teach skills ranging from stripmarking to interphone techniques. The students' tendency is to "work the traffic" and not give sufficient attention to the instructor.
As complexity and volume increase over time, the opportunity to instruct diminishes as the "machine" is now the prime instructor and interruptions may detract from its efficiency.
I agree that lo-fi sims, particularly early on, have great value. Hi-fi sims seem best for trainees in the final stages of development.