Pictures of the damaged side of the seal:
And the undamaged side:
It is obvious that no high-mileage or thicker oil would have ever stopped this seal from leaking. Slow it? Quite a possibility, but who knows. AAMCO claimed to have found no defects on the mating surfaces of the seal, but they did find two missing bolts on the bellhousing and replaced those free of charge.
The seal was replaced with a Fel-Pro BS 40631. I have read that Fel-Pro makes high quality gaskets/seals and try their best to remove OE defects and try to improve the design. I did not see this seal, but if I were really curious I could purchase one for $35, photograph it, post pictures here, and then return the seal. The job took about 6 hours to complete, but the shop kept the PF overnight to ensure there were no issues. I certainly hope this third RMS will not leak for another 100k at least.
The shop did not lose any fluids other than a very small amount of automatic transmission fluid when disconnecting the transmission cooler lines. I retained my engine oil and filter (as they were recently changed within the past 2000 miles) and all engine coolant. The work seems to be satisfactorily performed, and I am happy with the shop. I have a 90-day warranty on parts and labor. I'll likely be a return customer if the need arises. I will check tomorrow to ensure there are no more oil drips around the bellhousing.
I went with the dealer though because when I called them for a ballpark price on replacing the RMS the service advisor told me without me mentioning it first that they like to replace the upper oil pan gasket while they are in there. So I guess they convinced me they knew what they were doing. I didn't get to see the old parts but they told me the RMS was pretty trashed and was definitely the source of the leak. It was leaving a nickel sized oil spot everywhere it parked. I also had them do a couple of other things while it was there including replacing under warranty the driver's seat belt that wouldn't retract.