So the SD is "Gen4" Sigma? ;)
There is enough borrowed/new about this pistol to warrant a new name IMO. Like the FN FNP v FNX. It's not just the same dog w a new haircut, it's a new breed? Like Siberians and Malamutes; both "huskies", but not the same dog...
Whatever, I like 'em. Have put a...