id definitely think about not getting seths, period. For the amount of backcountry stuff that you say you do, the seth really isnt your weapon of choice, no offense at all but its way too wide of a ski to be runnin in the park with. Not saying you couldnt do it, but there are better alternatives for what you need. In terms of width, something in the high 80s underfoot is a better consideration. for example, a few skis i would take a look at:
armada ar6-- perfect half and half park/all mtn skis, dank in the park
volkl wall- i just bought a pair, and i can say they are amazing all around and aweosme center mounted, and fast as fuck.
head mojo 90- insane all mtn
i hope that helps a little, but its just an opinion, good luck etc.