I think it is unfortunate switch that you are hellbent on relying on a strategy that gives you a 50% chance. I personally feel that the game should start out with a roughly 50% chance of each side winning. The goal that I place upon myself is increasing my odds to something much higher than that throughout the game and then taking that chance.
I feel that by attacking karelia you are taking the chance that if you win, and win very strongly, it will probably give you the game. 50% of the time you won’t win the karelia battle, however, and you just won’t be able to recover. Yes you can hole up in germany and create a strong fortress europe, but with all of your armor and most of your inf spent, you won’t ever really be a threat. Okay, if you get heavy bombers you might be, but I find tech pretty cheesy in this case, and most others. Instead of using tech to make the game even, I would prefer to add units to give me that 50%, and then through good play raise my percentage. I define good play as a series of moves and attacks that give me favorable position and unit exchange. I guess I just don’t like the fact that the absolute worst player in existence could still win simply by rolling heavy bombers, whereas if they did not tech they probably never would. It does not even the ground between the axis and allies, it evens the ground between good and bad players. That is just my opinion though, and I wouldn’t even consider myself a good player, I just try to be.
In terms of karelia, if you take it and I have no transports as the UK I will hit it with naked air and clean up whatever is left. I’ll probably lose a plan or two in the process, but that’s the breaks. If you land your fighters from japan there, I will attack it with 2 1’s and 2 3’s (you forgot the fighter in the UK?) giving me a 80% chance of taking. We then trade for another round. Yes it is a pain if germany takes it, but that 50% chance is what irks me. If you were able to win assuredly after the 50% chance, okay maybe. As it is though, you could definitely still lose. If it pans out it makes the game pretty even, but if it doesn’t it makes it pretty uneven.
I’m going off of memory here, but with the odds I ran for karelia and the assumption that you were planning on hitting the canada tranny with a sub?, that leaves you attacking UK seas with 3 fighters, 1 sub vs. 1 battleship, 1 sub, 2 transports. That gives you only 70% chance of winning (combined with your other 50%), and when you win you will most likely lose at least one fighter, maybe two. If you attack with two subs and your three fighters, you have a 90% chance of winning, much better. It is still quite probably that you lose a fighter, though less so. Now there is a pesky transport that can go to karelia though, allowing the UK to take it back if you managed to take it in the first place. You could try and leave a sub to block that, but then you decrease your chances of taking and substantially increase fighter loss. Indeed, if you tried to leave a sub you would probably be down to 1 fighter, 2 fighters at most really. If you were only left with one fighter, I wouldn’t bother building a carrier and I’d just go heavy on the transports. If you took with two fighters, I’ll probably still have to build an AC, but at that point you would have a damn weak assault against the navy and in UK 2 troops begin landing.