Since nobody responded I assume I was the test case. I received the regulator today from Rock Auto. It appears to be a perfect copy of the OE part - the only difference being it does not have the M-B PN on it and it is made in Taiwan. It fit and worked perfectly
So, for you purists don't buy it unless you will be satisfied by saving at least 60% on a part nobody will see and which comes with a lifetime warranty as opposed to the M-B 1 year warranty. Since it takes less than an hour to R&R one it isn't really a big deal if this one breaks again during the car's lifetime.
One warning...you do need to save the small nylon slide which rides along the window's track from the old regulator and transplant it to the new one as it does not come with it. Since I didn't throw my old one away until after I was happy with the install it wasn't an issue for me but anyone who orders one thinking it is "complete" will be disappointed.
As an FYI Dorman also makes manual regulators which you could use to replace them if one breaks or to convert a power window car to roll-up windows. Also, the price is about the same at $60, so either way it is a substantial savings.