Some new technologies for infantry that I want to introduce and I shared at the forum a while ago.
I use Military Drums instead of moving Squires. The concept is close, although I ended up making Champions even 10% faster with the change of Squires.
In the Barrack:
Fencing School , or Swordsmanship School (IV)
Requires Gambesons (or maybe not). The Militia line upgrades are researched instantly (or very quickly), and the Militia line units gain +1 attack.
People would no longer need to wait the upgrades so long when they need to or want to use the Militia line. Even if they have been upgraded they could still have more attack.
Military Drums (II)
Infantry gain +10% speed. The prerequisite of Squires, and the Squires changed to give +10% speed to only the Militia line .
The faster Champions would clearly be more useful.
The Celts might have the Military Drums line provide +50% effect instead of the +15% speed.
Sack (IV)
Requires Arson. The Militia line units generate a few gold when attacking buildings.
Attract people to use the Militia line in the late game.