As a 2h cav player, I'd be happy with any kind of change to the 30% speed/damage nerf. Unfortunately, it is hardcoded, so nothing in that regard would change until WSE is in full swing.
A possible fix for this would be creating a new, very fast custom animation for 2h weapons on horseback, like the new hafted blade animations. After the 30% speed reduction was applied, the animation would then be more of a 'regular' speed on par with 1h weapons. I'm not actually sure if it's doable or would work, but it might be worth a shot. Alternately, an animation change could give 2h cav the reach bonus that 2h weapons get because of their ground animations, and thus differentiate them from 1h cav.
While we're on this topic, check out this thread:
http://forum.c-rpg.net/index.php/topic,10338.0.htmlThe great axe is the only 2h axe that's not usable on horseback, and it doesn't have particularly superior stats compared to other 2h axes. It should be useable by 2h cav.