If you go on vacation somewhere that will include diving, and your Perdix dies, will you be comfortable using the BUD as your main computer for the rest of the time? What will you do for an SPG?
Thoughts like that are why I would either use another computer that will read the AI transmitter (like an Oceanic Atom) as a backup, or I would use something like a Geo 2.0 as a backup (because it would work fine as your only computer, if the Perdix died) and take a physical SPG with me, to replace the AI transmitter with, if necessary. I don't think I would like it too much if I were trying to dive with a BUD as my only computer (in the event my Perdix died).