This DT-3 attachment to the Park TS-2.2 wheel truing stand gives the stand additional capability that will be used more often than the stand's intended function. With disc brakes, rim true-ness isn't so much of an issue as it is if you are running rim brakes. If your disc rotors are true, it doesn't really matter how out-of-true your rims are. The only thing the DT-3 lacks to make it perfect is the optional $40 dial gauge that enables the measurement of disc rotor run-out in both directions. If the dial gauge came with the DT-3 as a standard part of the package, it would get five stars from me and be rated as a good value.
I mounted my own dial gauge to the DT-3 and it is now a GREAT tool for keeping my disc wheels running (and stopping) well.
Simple and effective, worth checking the rotor every time you are truing a wheel as the rotor may seem to be running true but is actually close but not as good as you can get it using this. Of course the rotor does not have to be absolutely perfect to work well, but having it good does give you that "feel good" factor.