Firstly, ignore anybody who gives you a one word answer with no explanation. Chances are they have never skied either of the skis and base their opinion purely on what they saw Pep/Seth do in movies.
I havn't spent any time on the Obsethed but I've checked it out in the shops and skied a lot on the 08 Seths and Hellbents. If you're going to be charging more big mountain style stuff, or touring like Andy said, definately jump on the Seths. They are of course a bit more versatile all mountain. If you're more into skiing a little slower and jibbing stuff, landing switch, etc. then the hellbents are a dream. I'm a fairly big guy so I found them too soft for really charging but they are by far the funnest ski to jib around on. Its ridiculous how many possibilities the skis alone give you.
Pretty much you cant go wrong with either of these. Sick skis