Basically the escape and Ranger are the same BC... the escape is just a "lighter" version of the ranger (less D-rings, bladder size, weight size etc.) Both of these BC's should accomodate a 7mm suit.... the weight pockets on the ranger are bigger (20lbs each I think) and that will come into play if your a new diver with a thick wetsuit... both are great BC's but I guess the ranger has the track record and the escape does not. I own a ranger and my wife went with the escape... both have the same warrantee so thats a wash.... the escape has only 1 tank band and the ranger has 2, I've never had a tank slip out of my ranger during a dive (but neither has one slipped out of my wifes escape either)... I guess the bottom line is if you are looking to do some sport diving only go with the escape, but if your going to do a little "tech" diving as welll as recreational diving choose the ranger... thats my opinion, I LOVE MY RANGER and would not trade it for anything!
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PS... Ask the ntrox calc question in the tech section, you'll get 764 different answers!!