Everyone's needs will be different, but I'm finding Jumps to be more and more important.
I have two iPhones, two iPads (mini and pro), and the iMac.
And with the iMac, I would like three connections - one is the main one, one would be sort of a backup (only because I intend to keep testing things even after shipping and, if something does mess up, I want to be able to jump to a secondary slot in case it works. And I have a dongle for a 3rd connection to the Mac, just so I can be testing that as well.
And now I added an Apple TV. Now, granted, few will want to pair multiple times to their computer or would have 2 phones and tablets, but there will be folks who want to pair it not only to a home computer, but to a work computer. And I haven't included options where folks want more than one layout for different users (say, qwerty and Dvorak). And there there is the possibility of creating unique layouts for games or something.