Sparked by the new competitive map contest (see
http://atwar-game.com/forum/topic.php?topic_id=11572) I've designed my first custom map, based on New York City.
Following the guidelines in the contest post, the map is comparable to EU+ in terms of size, total reinforcements, and total income, though it plays a little bigger due to a greater land/water ratio than EU+. After a few test games (ffa, 10k) it appears to be well-balanced geographically both north v. south and east v. west. One unique feature is that air units are only available in the map's 6 airports (3 in the west, 3 in the east).
I'll keep testing, but I'd encourage others to test as well if they like. Search the maps for New York or my username, Matthewnym, and it will pop up. Here are a few screenshots: