from what I understand..the Stock II is built on the large frame gun..it is 3 ounces heavier than the SP01.
I found these on a shooting forum...the StockII looks great..
lot of great features..
upswept beavertail, ext mag release, ext. ambi safeties, big magwell, adjustable sights, FO front, overtravel stop, checkered frontstrap and backstrap, bull barrel, etc..
this will be a great gun...hope it gets into the US soon