I am also a new 15 22 owner and I also considered the Sig .22. One of my main reasons I went with the 15 22 is what you listed, was the folding stock. As my wife is not a tall person, thus shorter arms. The sig stock is longer than the 15 22, thus making the 15 22 easier for her to hold & fire. Yes the tactical look to the 15 22 also played a role in my purchase for the gun, but ultimately the expansion capabilities for factory "out of the box" that the 15 22 offers surpasses the Sig.

Both are very good guns. As far as accuracy, that depends on how well you shoot the weapon, but in general the 15 22 is dead on in farily tight groups, depending on the ammo your rifle likes. Now the older 15 22 models did have issues, but were part of a un official "silent" recall so to speak for lack of a better term, and all weapons were fixed free of charge and provided spare mags for the trouble.

My new 15 22 is a DUU serial numbered model with a threaded barrell. It has a mfg. date of 6-28-10 and has all the "up to date" specs from S&W as well as the Blue bolt and trigger springs. I can say that from personal experiences that my 15 22has fired about 350-400 rounds only so far during its "break in period" and I have had some FTF's and FTE's BUT those were ALL the non recomended Remington Golden grenades.. err golden bullets lol. While using Federal bulk packs it runs PERFECTLY smooth! My trigger on my 15 22 is not nearly as stiff as a friend of mine that has a older DTX serial numbered 15 22 that has, as of yet had no isses that require a return to S&W.

It all boils down to presonal preference, but while handling both model weapons at my local gun shop while figuring out what was the proper model to buy, the M&P 15 22 just felt like a better fit in both mine and my wifes hands. Where as im 6 foot 1, she is 5 foot 4, and the six position stock fits us both great. Hope this helps in at lest some way.