For some divers, those two things are pretty major.
I would also add a third disadvantage to the Petrel's list: Cost.
I shopped around and got my Atom with transmitter and data cable for $550, from an authorized retailer (my LDS, actually). I got my Petrel from the same shop for $750.
For recreational diving, I (me, personally) would much rather have a small wrist computer, wireless AI, and $200 in my pocket.
