the ar6 is fun, but i love the stl. i've skied the 07 and 08 183 stl in park and all mountain scenarios. they're really stable and carve great on high speed groomers. they're quick and maneuverable in trees and shallow pow. in the park, they're really light and poppy. great for anything from jibbing around to 60 foot tables. super stompy feel on landings. aaaand they ride switch unbelievably well.
the ar6 rides pretty much exactly the same with the main difference lying in the fact that it feels softer. i weigh like 170 pounds, so i really like the stiffer feel of the stl. if you're a little guy, however, you may like the softer ar6... that's a call you'll have to make.