In addition to all the other yay-sayers I want to express my approval too. "Main" is useful for high-quality content but it is useless with its current distinction between "promoted" and not. "Discussion" is full of stuff I do not care about or only very little, as is the case with "Main". Tags + "Best of" solve both problems nicely. For the tags take a predefined dictionary and users with high karma count have the ability to re-tag.

That way I can subscribe to the topics I actually care about and do not have to read about meetups on the other end of the world or some nuance of effective giving of money I simply do not have.

Oh and nice catch of the holding off solutions stuff.