I use a headset with option to switch between 7.1 and 2.0 (external sound card etc. blah,blah...).
And yes, the 7.1 actually has hearable differences in from where sound comes. I use it for FPS and I find it very, very helpful. At times in BF4 I could practically follow someone running behind a wall next to me almost exactly. Only judging whether something is above or below you is difficult (though that might be a problem of the sound mixing in BF4, I don't remember having so many problems with that in any other game)...
Mind you, I don't play many FPS games, but I feel it does make quite a difference. At least when you are able to hear things like footsteps and there is not too much going on. A game like CS:GO I could imagine 3D sound being absolutly vital. It depends on what kind of FPS you are playing. When you don't die very quickly or there is too much going on to properly hear specific things, having no 3D sound is much less of a problem, but in quieter games (or moments), when a single shot can mean you lose, it does help.
I would at least give your methode a test, see whether you like it or not. As you said, your ear is better trained, but still, if you can't make out the differences well enough, there's no point. If you can, on the other hand, I think it can be helpful. Unless it gets confusing for you...hm...I mean, it is pretty different from RL.