Better balance = upkeep is superfluous
Why can a guy with full Plate Mail jump? Or a plated charger? Or a guy in Full plate on Plate charger jumping over you head? Why does the plate guy not take much more time to get up when falling on his back than the peasant in cloth? Why do plate not slow attack speed?
Play with the mechanics, don't add grind that lifeless players negates anyway because they're loaded with gold. An army of tin cans should be an army of turtles: not viable and easy targets - even if they can take a huge beating.
People used plate to survive battles, not to kick more ass jumping head first in the opposing army.
There's many good ideas in this mod - upkeep ain't one of them. I personally like style over stats anyways, so you'll never see me in that horrible black armor ;)
Cheers,