I have a Goliath that I purchased a couple of years ago. I absolutely love it. Being a big guy, it's nice having the extra room to move around and becomfortable. I have used the Viper as well, and it works, but it's nice to have the extra room.
It is the best climber of the 3 I have owned. The only negative to it is that the paint seems to flake off rather easily.
Good luck.