I think it only needs a lot of testing, but extensive changes may be somewhat exaggerated. Except for the animation files (and only some of the 2H units actually need some faster animations), you only got descr_mount, descr_projectile, and EDU to change really for the most part.

If you really wanted to do even more, I suppose you could work the EDB to then control how many units you can hire of which unit, but that's about it.