I have had a sol, Luna, d9, and used many others. The d9 is a great looking computer. Issues is non user replaceable batteries and to replace it and do the "2 year" recommended service will cost you 200. Galileo, large screen, less conservative, user replaceable (though proprietary) battery. From what I see on the vyper air, the computer is essentially the same as the d9 in a puck style and no gas switching. Large easy to read numbers, you can get a bungee system, and a little less than the galileos. The one thing I don't like about the suunto's is that I always have to relink the transmitter and I always forget to change it to dive mode before u jump in and then don't get the pressure. Those are my big issues.
