I have one and love it. I hate starting up ArmA up without it. Infantry or not. it has become so natural that I will load up Project reality for BF2, start playing and start turning me head to see beside me. It becomes natural, on the ground or in the air, I cant play without it. I agree with GAU, if you don't give it half a chance you will hate it. At first it was awkward for me, I couldn't get the right feeling, but after a couple hours, couple days, it was perfect. Fling flight sims dogfights and low alt flying was 100x better. In ArmA, ground fighting was more intense. My Sit. Awarness went up huge once I got it, well spent money.
Have u ever been in a squad, watching you sector and you turn around to find that your squad has moved off? I did, but once I use TIR, I would glance behind/beside me quickly, and was able to keep my squad in sight.
I love it, well spent money, wouldn't and can't play without it. IMHO its worth it.
Agnew