Seems rock solid after replacing the thermostat and pump. Reset all codes and I'm still getting interior light codes, but don't really care
There was some coolant or oil on the pump housing when I pulled it, before draining so it wasn't coolant splashing back. The old pump itself *looked* fine. The impeller was not damaged, I didn't see any grit or shards in the drained coolant. Spun the wheel manually and it felt notchy, but I'm not sure if that's normal.
Hopefully I don't have to worry about this again for another 6 years. Was a bitch job to do with race ramps.
I'll call it successful in two weeks if no problems pop back up.