I've owned both the Walther and the Sig Mosquito, and can't recommend either one of them. I couldn't get through a single mag without a stovepipe, FTF, FTF, or a FTE from either of those pistols. I tried every type of CCI mini mag, Stingers, Velocitors, Fed bulk, Rem Golden bulk packs, even a couple boxes of Fed Match and nothing would work right.
The Walther was so bad that after 2 months I traded it on a NIB Sig, and from the very first mag had nothing but probs with it. After 6 wks and every type of ammo I could use, it still hadn't gone through 1 mag with a major prob.
Took it to my LGS and traded it on a NIB Beretta NEO. Now that's a nice gun. Came with 2 mags unlike the Sig (only had 1 mag) and it has shot every type of ammo even the Fed and Rem bulk packs. As for accuracy it is better than either the Walther or the Sig. The only plus I can say about the Sig is that it feels like a "real gun" as in (normal gun) in my hand.
I had owned a Ruger 22/45 for many yrs. After shooting about 30,000 rds. thru it the barrel and extractor became problematic. I sent it back to Ruger via my LGS with a check for $15 to handle the return shipping. I got it back with a brand new barrel and new extractor. I was shocked that I got it back so quickly, no bill for the replacements, and here's the kicker, they returned my $15 check uncashed....lol
The only prob with the Ruger is the take down and reassembly after cleaning, but that was the absolutely most accurate 22 I have ever owned.
I do like my NEO, even if it a bit futuristic in appearance, but it does handle nice, and I even put a cheapo red dot site on it.
Good luck and always stay safe.