I picked up a Shield 40SW recently and just took it to the range today to try it out. Shot about 75-80 rounds through it and it handled perfectly. The 40SW is perfectly manageable in the Shield and recoil is about the same as in my 40c. The narrower grip is not as comfortable to shoot as is the 40c, but is better suited to concealed carry than the 40c.
Only one problem, probably with me, not the Shield. I evidently need to work on my grip as most of my shots tend to be slightly to the left. They don't appear to be in one general area such as low and left, but instead vary from low left to high left. I may have to work on my grip, but if this trend of shooting to the left persists, I may look into having the front sight adjusted slightly .
But other than that it shot beautifully, not even a suggestion of a problem. I see now why the Shield has been so popular.