I'm not a big fan of the Act II starting positions. If you don't have the resources to overwhelm Karthan immediately, he does nothing all game but mass units at his capital and ocassionally attack yours with them. Sure, it increases the difficulty, but not in a fun way in my opinion. The navy issue just adds to that because you have no need for anything but transports in act I (and you can do even without those honestly), so you likely won't be prepared the first time.