Have not heard from Mr. Webb in a long time, but if you are still reading this thread, I have one of your mystery Sigma's. Sticker is missing from inside. It has the Greek Sigma symbol and the word sigma is inlaid in MOP just like the one you stated you had seen only one of before. I think it is a DR-11 from earlier descriptions on this thread, it looks just like the DR-41 but with silver tuners instead of gold and has a three piece back. It is easy to tell it is all solid wood, top, back and sides. Some finish cracks going with the grain but not into the wood. Sounds fantastic. Also have a
52SDR-9 with the earlier logo and snowflake markers. In minty shape. It aslo sounds great, like an aged D-28. If Mr. Webb is out there, please respond if you can, about the MOP SIGMA on the first guitar.
Thanks.