See my thread about the SD40; pretty much the same thing.
http://www.downrange.tv/forum/index.php?topic=13278.0I like these guns. I've been shooting them for a few weeks and they work fine, better for me than some guns that are supposed to be better and cost more.
It's not just a Sigma w a new rail. It's at least a Sigma w more than a few external and internal changes w some old, borrowed, and new parts. The frame has a new rail and grip, the slide M&P sights and extractor, the operating system has Sigma and M&P parts but some new ones too and is not the same as either...
Changed enough for me it's gone beyond the same dog w a new haircut; more like a new breed. Kinda like Siberians and Malamutes; both "huskies", but not the same dog.