John owns a complete Elite simulator, which he uses to help train instrument students like me. The Elite differs from my own little On Top simulator (or MS FS 2004, for that matter), by being approved by the FAA for training and (crucially) logging against required hours, and in its supposed levels of accuracy and fidelity to The Real Thing. The other main difference is that it has a full physical stack of switches and dials, so you change frequencies or set the OBS (etc.) pretty much the same way you would in a real plane (this is part of the FAA certification), unlike with a mouse the way I have to do it with On Top (the difference is pretty important when you're doing a complex maneuver or approach). The Elite works on a decent PC with the added hardware connected through USB -- i.e. (like On Top) it's not one of those airline simulators with physical movements, and it's not trying to do fanatically accurate rendering of ground detail, etc. (which would be lost on the average instrument student who only really cares whether he or she can see the runway at the end of the approach).
The Elite has two obvious advantages -- it's cheaper (John doesn't (yet) charge for flying it, only for instruction while I fly it), and it lets you set up all sorts of emergencies, approaches, weather conditions, etc., at the click of a mouse. You can do a hell of a lot in it -- like flying a complex approach to minimums while nursing a sick engine or failed AI -- that you couldn't do safely, or at all, in a real plane. And you can stop the bloody thing mid-approach and talk over what's going on or what I just missed, etc.
The inevitable disadvantage is that it's not a real plane, and doesn't really fly like one. It's better than my On Top, but it's still unrealistic in pitch and heading, and with no force feedback at all on the yoke, very difficult to trim accurately or to simulate things like sharp turns, etc. It's also weirdly unrealistic on final and landing -- I have literally hundreds of landings in real aircraft behind me, but none of them has never been anywhere near as hard as it is to land the Elite. Many times I don't even try -- the sensation of hanging there swinging helplessly a few hundred feet above the runway with almost no effective elevator or aileron control just frustrates me intensely (I usually try a victory roll at this point; if I ever persuade it to do that properly, that'll be a victory of sorts...).
In general I find it harder to fly in most situations than 05D, but that can't be a disadvantage in the long run. Still, it's an incredibly useful training tool, and it's all loggable time...