I work with beginning and pre-CHL level shooters almost every week in the classes we run, and several times a year we run pocket-gun and small gun specific classes.
Observations:
Springfield XD is popular, but has two major flaws: if the user fails to depress the grip safety, the slide will not move. This can be a problem when drawing the gun and particularly when those with small hands try to lock the slide back. Problem #2 is the stiffness of the magazine release. Both of those issues are frequently ignored or not observed by those that only do "target shooting" type practice, and never do any holster work, or any drills under time pressure or stress in their practice.
The little SIG 238/938 guns are OK, but the tiny little safety is yet another small control that can be missed or forgotten when drawing with any speed.
Glock 43, M&P Shield, and the new Walther are simple and tend to work well for everyone with the fewest problems. Those are the guns we recommend for those looking for a small reliable 9mm.
Karl
rehn@krtraining.com
http://www.krtraining.com512-633-8232