As for the magazine drop problem, check out a couple of the threads on here that have been ongoing for a month or so about, especially, the Shield 40. I haven't seen anything to indicate production has stopped until this problem is resolved -- in fact, there is rather widespread exasperation and annoyance that S&W does not seem to have addressed the problem that some Shield 40 owners (apparently those whose pistols were produced sometime after the first batch had been received by dealers) were having with magazines (especially the extended one) dropping from the pistol after a round was fired.
My Shield 40 came out in the first batch and I have had no problems whatsover with it, which makes me feel a bit guilty about and sympathetic to those who, based on the glowing initial reports, ordered the Shield 40 and experienced the magazine issues.
I don't think the 9mm Shields have experienced the same problem, so depending on which model you have on order, you might or might not have a similar experience once your third pistol comes in.
Welcome to the forum from North Carolina.