I've got a Cobra and my wife has the Gekko, both are consoles, and besides the backlight, guage mode, and PC-log connection, the other differences are minor. The logbook profiles on the Gekko don't have adjustable profile increments like my Cobra so the Gekko only can store 50 hours of dive profiles and logbook data. If I set my profile to 60 seconds I can get a 100 hours on the Cobra.
You need to think about whether you want the features that are missing.
Oh, one thing the air integration is nice on my Cobra it give tank pressure to the psi or tenth of a bar, and gives you breathing time left in minutes based on your consumption and the depth you at. The logbook also tells you how much air you used on the dive as part of the logbook information. They're neat features but not vital.
Both consoles have been great and would hesitate to recommend either of them.
By the way, the link to the thread
http://www.scubaboard.com/t51663.html has a post that says the dive history is 99 but it's really 999.
You can download both manuals at
www.suunto.com and compare them both. For the money you spend it is worth it the read all about them first. Happy shopping....