I've been using the Hitachi M12VC on my K2 3925 machine for about 7 months now. I like the unit and have a total of three, one is a spare the other has been set up for a specific operation on a Ryobi BT3000 table saw system. I've put about 200 hours on the spindle mounted on the cnc machine. I measured TIR less much less than 0.001 when I first got it, now it has about 0.001TIR. The spare shows less than 0.001 but is not as tight as the first one. I haven't checked TIR on the third (to lazy to dismount tonight). The one I use most is generating alot of brush dust in it, very apparent when blown out with air. Noise level was very low when new but has gotten louder with time and use, still lower then any other router I have heard. The load sense speed control works well. Only 1/4 and 1/2 collets are available, I am trying to get some 1/8 and 3/8 collets made to allow greater tooling choices. The collet adapters I have tried have too much run out in them for me to use trying to keep less than 0.008 part tolerance range(+-0.004).
I really like these Hitachi spindles.