so to follow up on Jim a bit.
What would you want/need to see on a computer from Shearwater, or what makes you concerned that the Petrel 2 won't be good enough? Bruce has made it abundantly clear they are not working on wireless AI, so that's out. You wouldn't want/need wired AI on a Petrel anyway, though I would have liked the NERD to include it for PSD and CCR use. Have two wired AI ports that you can put a QD on to monitor either two separate gas supplies while FFM diving or to monitor your onboard gas on a CCR.
It has an easy to use user-replaceable battery. The AA is part of the reason it needs to be as big as it is, but it's much more readily available than any of the watch style batteries and it's better than internal rechargeable because you never know when you won't have a charger on hand, but you can always carry an extra AA or two. This is a one-up improvement on the Predator because it can accept anything that is AA format.
It has a really nice screen. It is not OLED which was one thing that was better about the Predator, but it's still a damn nice screen, and any improvement is going to be marginal.
Bluetooth, Petrel 2 has a new bluetooth module that is compatible with iDevices, Android etc. so you can upload straight to your phone and analyze dives
Digital compass. I don't think it is a dealbreaker *I have a Petrel 1 with no intention to upgrade*, I prefer a slate for any sort of navigation work, but it is nice to have as a quick reference point
The only thing it doesn't have are any sort of alarms other than visual, but a lot of divers prefer that. Can't really add any other useful hardware into the thing. Everything else is software. It comes out of the box with Buhlmann with user settable GF's, has an option for VPM, so you're covered for anything you actually need. Has OC/CC fully unlocked, and the EXT/NERD have an SCR setting for babysitting SCR's. I would like them to improve the desktop software so you can program the computer from the desktop software. Upload gas mixes, dive plans, settings etc. would make it a lot easier for those of us with multiple computers to just mass upload everything, but that is a software change.
If you're worried about support, they still support the original Shearwater GF and all of the other products they've made, so I wouldn't worry about that.