I have the V1 mill with the CPU inside the CD100, and have been generally satisfied over the past 18 months. I don't do production, make small parts, and rarely have a single run over 30 minutes, and never let it run unattended. I have seen the following happen on occasion:
I leave the machine powered up for a couple of hours, not running. When I return none of the axes respond to jogging. I restart mach3 and it's all normal.
A couple of days ago a similar thing happened during a run. Both the spindle and all axes stopped, and none responded to mach controls (mach showed spindle active). I recorded the 3 axis settings, restarted mach, and was able to continue the program.