These changes look good, but I think you need to remove the 60 base tax cap for Marches. Not being able to annex them is enough IMO. You're committing a diplo relation for most likely the rest of the game, you should get some real benefits.



As it is I've never seen a reason to make a march. If they're under 60 base tax I'll annex them, and if they're big enough that diplo annexxing isn't feasible I can't make them a march. That's where I'd want it most.



Maybe scale the bonuses down a bit, but the 60 base tax limit basically assures that what could be a cool feature is never used.