With only the skin being transferred, you don't have to worry about speed/ water and etc.
what he wanted transferred was the speed not the skin.
Tbh, to me the mounts should be purely aesthethic. Should all be the same speed. Only have the regular special fly on water/multiple seats depending on the mount.
Otherwise there's very little point to have slow mounts ingame UNLESS they went on sale half price for happy hour. Barely get to use them as they provide nothing other than a different look. I'm looking at all those 65% mounts.