I sent an email to Meyle, and here is the response I received:
"Actually the design comes from the earliest version produced by Mercedes that were used in the M116 and 117 motors from the early 1970's. The idea to reproduce the chain rail and an OE sample of the original was supplied by a Mercedes Benz repair specialist in Bellevue, WA in 2003. He supplied us with the rail and was the first to get a production sample and approve of the design.His name was Frank Schmidt but he has recently sold his repair shop and retired due to health reasons.
In 2002 MEYLE Products purchased their own rubber to metal products production facility and hired a number of rubber to metal engineers from OEM manufacturing companies to design and over see the production of all of the rubber to metal products offer by MEYLE Products. See
www.meyleusa.com for information on the different HD products offered by MEYLE. . . Close to 400 pieces of this chain rail were sold in 2007 to different warehouse distributors on the USA. . . Since the release of this version of the chain rail 3 years ago I have not received any complaints that the rubber separated from the aluminum. I have not received any complaints at all for that matter."
I'm just very surprised that very few people have apparently ever used or even heard of these rails, given the tendency of the plastic rails to crack, and the cost and difficulty of replacing them every 100k miles.