I don't use it because (A) It prints more, and (B) More importantly, my gun tends to drop the mag when the extension is on it. I took the extensions off, and voila! No more dropping mags under recoil. Problem solved.
Apparently this is a common problem. I posted a question about it and got a few replies stating that others had this problem too.
Im exactly like spikedriver. I had problems with the mag dropping with the "pinky extension" I changed to the flat floorplate, and over 800 trouble free rounds, and counting. I like the feel of the flat floor plate now, since Im used to it.
I like them. makes the weapon easier to grip and shoot. that little snot doesn't print that much but it sure helps me. no problem with the mag drop. my concern is the first 11 shots then I'll worry about the reload. carry two 17's for that. opps! no guns no ammo ---hear that NSA????