Actually I like some of sado's ideas, like:
-make them hit the enemy troops very fast (to make it good against bowmen... just hit and run)
Something like charge possibility for them, but instead of faster movement, make them be ready to attack immediately as they reach enemy troop (now every unit first got engaged in battle, then make first hit). This will make them more powerful against ranged. But on the other hand, they will be more powerful against every unit, which can make them too powerful.
-make scouts uncatchable by ranged units - I mean: infantry and cavalry can catch them, but if scout is killing ranged units, he can always quit doing that and flee (this idea might be a bit against KaM spirit)
This would probably be solved when they had this first ability, to make first hit faster.
-make them able to steal food from the enemy
This idea could be good for vagabonds (yes, vagabonds, if we are making changes for scouts, why vagabonds shouldn't have them? But this idea is for different topic).
I imagine, that every mounted unit should have it's own ability. Vagabonds - stealing. Scouts - charge. Knights - well, they just powerful, that's enough.