Matrixi, locking at 100fps makes it far less smooth than locking it at 60 or 120(ish) for me, by an absolute mile. It brings in a serious micro-stutter at all times, feels like when I'm going round a corner the car is stuttering round it, it's not nice at all. I actually have the same problem with iRacing, in the 70 - 110 range it's an absolutely stuttery mess for me, 120-124 is perfect and 60 is passable. There is also the advantage of 60fps vs 100fps which lets me bring some eye candy back in.
I never really had a problem with tearing, that's not one of the reasons I went with vsync to be honest. I also didn't actually notice any increase in input lag either, which goes against everything I've ever heard and experienced with vsync too. This is obviously with all the usual nvidia settings (pre-render=1, max performance, LOD clamp).