I do not like it. Dont get me wrong the idea is fine but... I have thought about it before...
What will counter horse archers? Nothing at all...
You send you 5 paladins at the five horse archers expecting easy slaughter... But there they go running and firing at the pals as they move... The pals arent making any gains on the horse archers, and even if one did get close and cut one of, there is one chop and the horse archers are out in front again...
Literally nothing would ever catch them...
Avengers idea about weaker hp?
So what, if you cant catch them it will not matter. Horse archers already have typically low hp, and thats why they arent used in the frey. If people cant catch them it wont matter one bit...
Lesser accuracy?
Still same thing. If 1 out of every 4 arrows hit, if one out of every TEN arrows hit, it wouldnt matter, because the horse archers are moving and nothing will stop them until ... the ... enemy... is... worn... down. . .
The only thing I can think of that would make it... sort of balanced was if you made the archers REAAAALY slow when they were firing arrows in movement... Not only is this realistic as no one can peg someone from a full galloping horse backwards a long way away, you have to slow down! Also it would allow fast infantry and any calvary to catch the pesky archers and damage them...
My thoughts...
-Vladimir87