My personal issue w/ the Walther is the slide mounted external safety. Some of my cc guns are 1911's. The Walther safety operates the OPPOSITE of the 1911 (and most other semi-automatic pistols) in that the shooter thumbs it UP, rather than DOWN, to deactivate the safety and shoot the gun. The only Walther P22 I shot was not very accurate, but that may've just been bad luck.
I'm not sure exactly how the Sig slide mounted safety operates, but that might be something to consider.
For you Sig Mosquito shooters, how does the slide mounted safety work?