Thing is, most people with large armies are not leading the tech game so it isn't a balance issue. If you have the largest army(highest on powergraph) and leading the tech race(Most advance, meaning well developed science cities), and can be a wonder builder, move up the difficulty level asap because all three at once is impossible unless you are using the World Builder.
Why group GGs into Warlords when basing them for exp points is a better option. Cheaper upgrades makes it better for builders since they aren't having much of an army as it is. Thus this will make it somewhat fair. More times than not, building a large standing army, you would not need to upgrade as often because it would cost too much and you are always making more units, outdated ones become the pawns of war.
