Well, I installed the PCM at the junkyard and drove home. About 30 miles, mostly expressway, some suburban roads. And...
The car feels completely the same. What an experiment. At least shift points are exactly the same from what I can tell. Idle seems less rumbly, but maybe that's a placebo effect (?).
Based on the door sticker, I have an older tune. But my PCM was a remanufactured unit, so the actual tune may not match the sticker. The junkyard PCM has a newer tune per the sticker (the one from the torque converter shudder TSB). Also, I think the junkyard car does not have a NY/CA tune which mine does.