I have one and have about 100 rounds through the mag with it. Feeds great, no modification done to it. I prefer it over my Pearce. I have or have had just about every mag extension/base plate for the Shield. My Favorites right now are:
Hyve +1 for 7rd (carry light clothing, min capacity)
Recover Tactical Mag Clip 7rd (extra carry mag, min capacity)
SI +2 for 7rd (carry, heavier clothing, max capacity)
Stock 8rd with NeoMag (extra carry mag, heavier clothing, max capacity)
So the combo's above allow me, 7+1+1, and 7 or 7+2+1, and 8, I either carry one of those 2 combos.
Here are some pics for comparison purposes. I currently do not have the Pearce in the line up and I sold my Hyve +2 for the 8rd. It made the grip too long especially for edc for me.
