Check the manufacturers web sites, some of them let you download the owners manuals, which may help you in your decision. That's what I did, and ended up buying the Suunto Gekko. It has a few less bells & whistles than the Vyper, but it's a very nice computer, is nitrox capable, and it won't break the bank. The Suunto RGBM algorithm is rather conservative, just so you know, but I see that as being a good thing.