It would be nice if you were able to exchange one type of xp for another. Exp. Trade in 5k xp for 3k prime xp, or 5k prime xp for 3k legend xp. Should also be able to go the opposite way. Exp. Trade in 3k prime xp for 5k xp.
It would also be nice to have the option to trade in inactive players for xp or evo coins. It cost too much to evolve players past gold level.