Great choice! I made the same decision last September and couldn't be happier. It's now my only gun and I feel very well protected. My wife's got a Gen 3 Model 26 but we might try to upgrade her to the Gen 4 because the grip is a bit smaller and might fit her hands better (not that she shoots that much, about once or twice a year).
Regarding the magazines, I can shoot the gun fine with the stock mag, but I do like the feel of the GAP floor plates and the Glock 2-round extensions for various methods of concealed carry. For home defense and a spare, I usually can lay my hands on a 15-round magazine with an X-Grip adapter. I used that setup for shooting the IDPA Classifier match this spring and managed to squeak in to the Expert class of the Stock Service Pistol division. And this came about after five years of being stuck as a Sharpshooter when I was shooting .40 caliber Glocks, including a G35.