I find that the nipple requires a little too much pressure (T500), which is a little tiresome. You can be really light to the touch with some touchpads (including simulated clicks.) I'd prefer a nipple more like a touchpad - something like you get on the Blackberries (not the old trackballs.)
I've tried playing around with the trackpoint speed under Xfce, and it doesn't help that much. The pressure needed although not much, is enough to put stress on my upper body.
