Not meaning to "flame" anyone here, but I thought I would put my two cents worth into this thread based on what I've learned. First off, CR10xxx is an early stainless serial number alright, but it's my understanding that the first stainless serial number was actually CR10000 (instead of CR10001). Apparently the headgunsmith still has that one in his safe. Secondly, while they did stop engraving "Professional Model", it wasn't engraved on any gun; only on the shiny sided MK IV blue guns and shiny sided MK VI stainless models. (The matte finished, stainless MK V's were usually engraved with "Combat Master" under the "Detonics 45" on the left side of the slide). You're right about the Combat Selector sights being shipped with the MK IV's and MK VI's.
Well, maybe not quite two cents worth, but worth noting anyway.
...Deeton