After seeing how my game vs NCC as an Ally is developing, to test All-in defense, I have contrary thoughts.
NCC has made a cautious attack protecting its tanks, advancing slowly but surely.
Its casualties will be reasonable (+ -200 troops / + - 100 aviation) and France will fall in August.
He can choose if he does not want Vichy because he has massacred the French, he has taken advantage of BOA which will prevent Uk from helping the Soviets a lot when Barbarrosa arrives.
When you lose 4 tanks it is a big problem, NCC will only lose 4 Corps, I think this is not fatal.
I think the real problem with the All-in defense is when the Axis player uses Blitzkrieg (except LiquidSky's Blitzkrieg), but NCC has made the smartest attack I've seen against this defense that I thought was insurmountable.
So, all-in strategy does have defense.
The future change in CV air power will help Axis gain air superiority, and Uk's initial troop reduction will also help make this defense even more risky for Allies.
This game will be matched after the French campaign, and it remains to be seen how many English troops will be able to escape from France. We should see in several longer games what is the real long-term price that the Allies will pay for using this defense.
But I'm worried that this defense will ruin the game anyway, because if France falls late and wears down Axis a lot, the game will only have one way for Axis (to conquer minor countries and wait for Barbarrosa, not Africa, not the Middle East, not SeaLion , not Spain) in short, few strategic options and that's not fun.