My wife and I just shopped for nitrox computers to replace our 6 year old very basic non-nitrox Suunto/TUSA wrist computers. This board and some others were very helpful. We sat down with the user manuals and worked with several computers for 15-30 mins each. We were down to the cobra and the uwatec air Z nitrox both of which are air intergrated. The cobra is very sleek and attractive and I had to keep reminding myself that "cool looking" shouldn't factor into our decision. The Cobra also had the compass option which fits on nicely. The Cobra has many user settable options, but these options fit into multiple layer menus which were difficult to sort thru as a new user. You may get to know them, but with my diving a few times a year, I would always be using the manual to figure out which menu a particular option was in because the menu "titles" weren't particularly intuitive. Needless to say, the flexibility of the Cobra seemed pretty good. Lots of things that you can change without a computer hookup. It also comes with an optional quick disconnect which would be important for us to take back to our room or into the lounge to write our logs.
We chose to look at the Uwatec air Z nitrox rather than the Air ZO2 because the ZO2 eliminated the dive planning options to add a rebreather option. Otherwise, they are the same as far as I know. We use dive planning a lot and don't see ourselves using a rebreather. We bought the Air Z nitrox and used it for a weeklong trip 2 weeks ago. I really like wrist mount so I always know right where it is and so I don't have to deal with keeping a quick disconnect clean. Changing to nitrox is a piece of cake and can be done to any increment of 2% between 22-50. You can dive nitrox and then air and then back to nitrox or whatever combination you like during a day. We bought the software and the memo mouse. The computer stores detailed dive data for about 200 minutes and then you have to move the data to the memo mouse or it spills over and the lose the older data. Memo mouse download is a 10 second deal and can be done for 2 different computers into the same memo mouse. You do need the software for this computer to change some of the alarm levels and a few other settings. We lowered the "high breathing rate" alarm and it was still too sensitive so I can't imagine using the computer without lowering it somewhat, else the alarm would be going off a lot. The software is easy and straight forward.
In summary, I found that the air z was a little more user friendly, I liked the wrist mount, I liked the menu system better, I liked the software and memo mouse, I liked the big digits on the air z, and I liked the overall ease of use. By the way, we bought them with full warranty from simplyscuba.com in the U.K. for half of what it cost here in the U.S. No import duty. Express shipping in two days. While I am a big fan of our local dive shop and supporting them and getting local service, that big a price difference pushed me to the online purchase. I have bought several thousand dollars of gear )(b/c, regs, and more) at our local shop and they have been great.