I have a Summit Viper SS and I love it. I just looked at all three of those websites. They each have the Viper SS for about $260. I didn't see the other models you mentioned. To me, if it's not a Summit it's not a Viper. The Summit Viper SS comes with a harness so don't pay extra for one. You don't need a DVD, EZ Hanger or a decal either. Spend an extra $30 and get the climber you really want to be holding your butt up in a tree.