I too have a love/hate relationship with Mindanao. It's a beautiful map. There is a nice selection of altitudes. All in all, very attractive.
However, it has two problems from my point of view.
1) The fields are so close together that field capture is extremely difficult, thus Mindanao drags on and on and on. Remove 25% of the fields and you'll solve the problem.
2) The country with the Westmost island has a terrific advantage. It's difficult to attack their HQ and all capture attempts have to start at the neck area. To be sure, you can sneak capture a field, but there's no way to support it once you've got it!
Rather than removing Mindanao, I would prefer to see some fields removed. Don't see any obvious way to fix the West island problem.
AKcurly