If the goal is to reduce server calculations in cyrodil, why not go ahead and remove the upgrading/downgrading of forts and take away the ability to destroy and rebuild gates and bridges? These things don't add much to the game play, so it's it's just extra calculations that don't add much to the game.
I mean, the upgrades/downgrades based on which resources are owned is a great concept, but if it means smoother game play in every other way, it seems like a good trade off to me.
How about we at least test this and see?