Something to chew on. There is a reason that Glocks are carried by something like 65% of US law enforcement agencies. The main reason is the proven reliability. The XD's simply do not have that record under their belt, and to add fuel to the fire. Some of the departements around here have removed XD's from there approved list of weapons, because of the cracked locking blocks that have been found on some of them. Even at low round counts.
I am not saying the XD45ACP suffers from the problem, but the fact of the matter is, the 45ACP in XD is an unproven platform, and some form of extremism had to be implemented in order to squeeze that many rounds in that size of a package. It remains to be seen if that will cause problems in the future.
For the record, I own all three models of 45GAP Glocks, and XD's in 9mm, 45GAP, and the tactical 45ACP. I am still building my trust in the XD's but I have not had a single problem with mine to complain about. For duty carry, for the time being, between the two I would carry the G38, with back-up magazines with +2 extenders on them. And to be honest with you, I would probably go for a G37 instead of the G38, unless it was for concealed carry in addition to duty use. I have not had a problem finding ammo and there are slowly but surely more departments adding the Glock GAP's to their primary or approved to carry lists.