They had a "unique" experience, whether that can be classified as "real battle experience" on the other hand is hard to say, and frankly is more of a matter of semantics IMO.
TBH, you're over-simplifying things here a bit, and frankly it's to be expected as not many people actually have real world battle experience. Fatigue, stress, pain, injury, your body's physiological reactions to these stimulus, amongst other things, are not things that can remotely begin to be replicated in SAO's VR environment.
And they're not the least important. If anything, they're some, if not the most important factors on a real battlefield.
Nope.
Simulators are used as
complementary tools in military training, primarily due to cost/time considerations. It doesn't matter how many hours you log in a simulator, it does not replace the actual hours that you'd need to log in an actual plane.
A VR simulator, especially one at SAO's level, cannot replicate the myriad of physical forces that will be exerted on a pilot's body, it can't accurately replicate how a user's body will react in a real world scenario, which greatly limits its usefulness as a primary training tool. There's a reason why we're still using live-fire range for training, instead of using only the ISMT - the same principle goes for both military and civilian pilots.
Now if you're talking about a Holodeck, that's another story
