Yep. Warlord Edition/Mongol Invasion changed and added a bunch of stuff. One other difference was that Geishas, which took 4 seasons to build in the original, take 8 seasons in WE/MI.
I don't think it really reduces provincial management per se; it just changes the rate at which you can develop your infrastructure and expand. It allows for better units sooner, and more of them, which I find to be nice. I used to get pretty tired of fighting the majority of battles with huge stacks of nothing but archers, ysams, and ashis.
Definitely try the 1530, 1550, and 1580 full campaigns. They are rather different than the original Sengoku Jidai. Even the Sengoku has little changes from the original (like a Legendary Sword Dojo in Tosa at game begin--a niiice target for the Shimazu).
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