Faster disks and disks that can be recalled with would be uber. A dragon's disk that can hold multiple items, I would melt at the sight of one of those - too bad that's not an option to vote for
It would also be nice to see some new and nifty art for the older biped cargo disks, but I'm guessing that might've been though of already.
Personally, I could think of better things to improve upon or revamp other than cargo disks. They're hardly the source of the often mind-numbing grind that one can experience (though draggin it around for miles does seem to add to that..) But, those're just my little tid-bit thoughts that I wanted to jam in there.