Specifically what I'd like to see is 2 things:
1) Each disk line (standish, Tarbash, standard, etc) have different tradeoffs. This exists to some degree right now, but what is the tradeoff between a Standish and a
Standard or a Delux? Nothing really.
For instance Tarbashes can hold darn near a silo worth of material (+) and they can teleport (+), but they are slow (-), they can only hold one type of material (-), they have a high useage level (-, but only when you are still leveling), and they can't recall (-). That is the type of tradeoff every disk should have.
Every disk should have different properties that make a person think about which type of disk suits their needs the best. And each disk should still be useful.
2) Instead of having Speed Caps on disks, have the speed reduced by a fixed number or, better yet, a fixed %age for each disk. That way things like sprint and boots of speed and wingscales would be helpful.