I used a MS trackball (thumb operated) and it read me as 9 years younger than my actual age. I expected the trackball to be a significant handicap, but maybe it's not? It certainly felt like I was struggling to hit the targets, with plenty of overshoot.
I also used MS TBO but in my case it guessed few years too much. I'd say it's interesting if there was a single person here who didn't get answer between 25 and 35.
And TBO definitively is a handicap, try playing Quake with it if in doubt.
