I had the clark nx150 for about a year and then the wbbb and now i have the wbrr. I did not like the nx150 for many reasons lots of calf pressure and kind of heavy also z liner did not keep me warm because of the gaps between them. The wbbb was great accept for i always had a problem with the uq would not stay underneath me at night which is very frustrating but less calf pressure then the genius brandon came out with th ridge runner all my problems have been solved thank you brandon ps the lynx never moves and the lay is 100 % flat