UPDATE – 10 Jan 2015
Good news on this front. Everything you read below is accurate, but here’s what changed with Apple this week in the US:
First, they are selling the “more worldwide” version “SIM-free” at their stores. This means you won’t have to go overseas to purchase this version! Fantastic!
Thus, you’ll be choosing between two versions, even though they won’t say it. If you want the A1522 version that works well in the Caribbean and other places, great! Get the T-Mobile version. If you want the one that works well in Europe and Asia, buy the “SIM-Free” option, A1524.