Cage, love your concept. One comment from me though. You know how most of the smaller MA maps have a 'winner corner' and a 'reset corner'?
From your last image It looks like NW has the advantage with a more compact home island, making defence of the whole land mass easier while the other 2 home islands are slightly longer and thinner. Makes defence more spead out.
Also look at the distances between all of the main land masses. The NW has quiet a lot of water between it and the other two islands. The NE and S island have only around 4-5 sectors at their closest point.
It's really hard to fit 3 sides equally onto a map which is square. I just feel the balance is slightly too much in favour of NW at the moment. Sort of like the West side on Mindinoa or the North side on NDisles which very very rarely get reset. Gut feeling is that S would end up as 'reset corner' and NW as 'winner corner'.
I like everything else. Good luck
Gatso