Finally took the plunge. On the left is an estop wired between the main board and the AC servo drive enable line. I was very uncomfortable that the only thing standing between my spindle and the on state while I was changing tools was a windows application. Now, I can change my tools without having to get up and switch off the 220V (The main estop turned off control to the machine completely, which is not what I wanted since CutControl wanted to rehome when the main estop was reconnected).
On the right is the cabinet estop, wired in series so that either estop will do the job.
