There would have to be some modification of the speeds considering that some are able to move faster than others; otherwise, this is a neat idea! Maybe it could be a pit like the pet derby where the speed is all standardized excluding the 'trip-ups' or 'speed-uppers'.
The mounts speeds would only be faster in the racing area/track and on the streets they would all have the same speeds that they do now and when you go and buy a mount you would see a racing speed along with normal travel speed there would also be power ups and what not you could buy for your mount to make it faster
