I was thinking about the smoothness of this and the aimtrak device itself, but people using the aimtrak say it is really good, not sure if the technology used would be any different to a wiimote, as they use an IR bar as well it seems.
I didn't know one could connect a wiimote to a PC via bluetooth rather than an IR bar? I might look into that ... and see what demulshooter offers, I've heard about that programme but never installed it yet...
Smoothness shouldn`t be that much of a problem. the connection via bluetooth was the first way to connect a wiimote to pc, and it`s nice to experiment as the bluetooth dongles are cheap. Also, the sensor bar is just 2 ir leds, so something home-built with 2 ir light sources should be fine.
If you would have to buy a wiimote to try this, I would recommend just picking up aimtraks, as they are the most convenient, or, if you are not afraid of unsigned windows drivers and somewhat "unfinished" software, ems topguns.
As for the wiimotes, just beware of clones, they aren`t as good as original ones, I have both the clones and the original wiimotes.