The Hellbent didn't change, other than the topsheet, from 2011 to it's final year.
I've owned a pair of 179 2011's and 189 2012's.
The 189 is a way better ski if you can handle the additional weight and length. Both sizes rock in pow (duh) but the 189 is way more stable at speed and handles chop/chunder/crap a lot better.
They're relatively traditional in their design, in that they only have a very small amount of early taper and the sidecut, rocker and flex profile is pretty "normal" - this makes for a predictable, although not exactly exceptional ski.
They are heaps of fun, slay the powpow and work surprisingly well on snow that you wouldn't expect them to.
Alternatives that spring to mind are Atomic Bentchetler, Line Opus, Volkl Chopstick... there's heaps more of course.