We know there are 2 levels of horses in ESO. The 17k horse (15% to run speed) and the 42k horse (25%run, 15%run/10%stam, or some other mix).
As you level a horse (through feeding,) it's stats will improve. It gets faster, more stamina or a larger carrying capacity.
What I want to know is if at max level will the horses even out or will the basic/starter(17k) horse always be behind?