I have trackIR. Had it fir years but I use it exclusively for flight sims. I'm a big proponent of sim racing too, but I don't use trackIR for that. For some reason I find it slightly disorienting when cornering. Others swear by it for sim racing though. Its a must for flight sims for combat / runway situational awareness.
You mention ETS2. Well, thats the only other game I use it for. Makes pulling out of intersections without causing pileups so much easier. Its very beneficial for ETS2.