If Aoe1 units were playable

How would this affect aoe 2 gameplay?

Say there is an option for aoe 2 players to enable training Aoe 1 units. How would this change gameplay?

I'd imagine almost all infantry would be swapped for Academy units. Scorpions and onagers might go extinct in favour of the more powerful catapults/ballistae. And the Egyptian priest seems pretty terrifying.

Aoe 1 war elephants were also mad iirc. They seemed far tougher and had splash damage compared to aoe 2 persian elephants.

Any ideas?