You did bypass the ESC, correct?

The '7427 has the knock sensor connect directly to the PCM.

I don't remove power from the ECM, or unplug it when I swap EPROMs, never had an issue.

In a friends car, I do use a remote socket from Moates (Chip Extender 1.0), and just swap EPROMs using that and a ZIF socket. I tune his car using an Ostrich though.