Note that the feeding problems have likely nothing to do with the polymer lower, but with the general design of the .22lr action of the particular gun you tested. I had about 3 FTEs in over 3000 rounds in my S&W and those were ammo related. It is my understanding that the Colt does have a working dust cover, which the S&W does not. The Colt also has 30-round mags, while the S&W has only 25-round mags. It is also my understanding that the S&W is easier to disassemble for cleaning.
My setup: a S&W M&P 15-22 MOE with a Magpul AFG, Bushnell TRS-25 red dot, and Primary Arms 3x magnifier with flip-to-side mount. I recently added a SOE Gear single-point sling (not in the photo below). The MOE already comes standard with the Magpul MBUS and grip.
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Colion Noir's review: