So, there's a pretty severe drawback in DF2014 right now for long-term play.  World history runs fine, but then as soon as you start playing a multiple year fortress, the world map goes to hell in a handbasket.

Here is the year 500 diplomacy map, compared with the year 503 diplomacy map:



And the year 500 trade map compared to the year 503 trade map:



Civilized World Population (year 500)

7397 Dwarves
14956 Humans
10556 Elves
82695 Goblins
505 Kobolds

Total: 116109

Civilized World Population (year 503)

7222 Dwarves
15661 Humans
9737 Elves
53915 Goblins
561 Kobolds

Total: 87096

The world map also shows a lot more ruins.