I wanted to add one additional follow-up.

Last week I spoke to a guy who distributes the lube I've been using. I sent him the same picture which appears on page 2 of this thread, which shows the chain with about 1,500 miles of wear on it, stretched to just shy of 1/16". I recounted to him the ultrasonic cleaning, etc., and got some suggestions in return.

Basically he said that Simple Green is fairly aggressive and acidic, and it almost certainly removed all the polymer which had supposedly been built up by repeated applications of Dumonde lube over the initial 800 miles. He recommended not using Simple Green in the future, and if I choose to clean the chain using the ultrasonic cleaner, using nothing but soap and water.

According to him, the repeated application of the lube causes a layer of polymer to grow on the chain, so that one can go more miles between application without noise from the chain (they recommend applying the lube only when you hear your chain squeaking/making noise). He wouldn't give me any hard numbers, but claimed to know high-mileage riders who deliberately overlube their chains with this product and achieve extended chain life (beyond 2000 miles).

Finally, I asked him about applying the lube correctly. His advice was to apply and ride immediately, as the oil contains an aromatic compound/volatile carrier which will work better if the chain is in motion, carrying the lube throughout the chain. I also asked about the necessity of first degreasing the chain, and he said it most likely did not matter, as the Dumonde lube would actually displace the grease.

So anyway, I'll replace the pictured chain soon, and follow up with this thread as the situation unfolds.