My observation: They don't mix.

I was having hot start problems, so I thought I'd do belt & suspenders - high torque permanent magnet mini starter and remote starter solenoid.

What happened is the starter wouldn't disengage right away after the engine started. The theory is the starter becomes a generator after the engine starts, and since the motor and starter solenoid are tied together by the bus bar that you use with the remote solenoid, the starter solenoid remained energized and kept the Bendix engaged. After returning the wiring back to "normal", with the starter wired directly as stock, the starter began working as expected.