Upgrading to Man-at-Arms takes 40 seconds, to Long Swordsman another 45, to Two-Handed Swordsman another 75, and to Champion another 100. In total, that’s 260 seconds, or over four minutes.
Because of this, switching from Militia to Champions in Imperial Age is very time-consuming. For comparison, upgrading from Archer to Arbalester takes just 85 seconds (35+50) and Spearman to Halberdier takes 95 seconds (45+50). And while Knight to Paladin actually takes 270 seconds (100+170), this is mostly due to the very time-consuming Paladin upgrade.
One way to solve this would be to reduce the upgrade time from Militia to Man-at-Arms in Imperial Age. This would be an exception to the general rule that upgrade research times are always the same, but since Man-at-Arms is the only unit upgrade in Feudal Age, I don’t think that’s unreasonable.
For example, in Imperial Age the upgrade wouldn’t take 40 seconds, but just, let’s say, 10 seconds (the same as Sappers). This way, upgrading from Militia to Champion would take 230 seconds, instead of 260 seconds. Still quite long, but at least less than four minutes. If you do the Man-at-Arms upgrade in Feudal Age or Castle Age, it will still take 40 seconds as before.
Good idea? Or would it be too confusing?