It's kind of a mix between the two. Except there aren't any given classes, just weights. The heavier you are, the more health you have, but the slower you are. Besides that, you just choose what your character looks like, and what weapons/items you have on them. It works really well.
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Xbox GT/PSN name: TatteredUniform
http://www.scuffletown.org/wp-content/uploads/2010/05/tRBE1.gif