Here are my impressions after demoing a whole slew of skis in this size.
*Snow Conditions: Powder ---> Packed Powder/Crud (over the course of 3 days)
*Demo or Purchase: Demo, then purchase
Height/Weight: 5'9", 150
Average days on snow: 11-25
Years Skiing: 15+
I spend most of my on-mountain time at Stratton and I wanted a single ski for most Eastern conditions. Hard snow grip, mogul performance, and stability at speed were my main criteria.
Nordica Enforcer, 161cm (all they had):
These skied pretty narrow for such a fat ski, but I still found them unnecessarily heavy for such a short ski. These weren't terribly fun on groomers as they were a bit slower edge-to-edge than I like. In the bumps, they weren't much fun, but they weren't too bad a liability either. I really don't get why you would have these on the East Coast.
K2 Aftershock, 174cm:
I really didn't like these. Lifeless on groomers and not much fun in the bumps either.
Dynastar Sultan 85, 165cm:
I was pretty sure that I would like these, and I did. Nice balance of skills, fun to carve with, and great in the bumps. Not super stable at speed though.
Dynastar Sultan 85, 172cm:
These had the stability the 165's lacked, and pretty similar in the bumps. These also floated quite well in the powder on the sides of trails. I liked the added stability vs. the 165s, but didn't like how they felt a bit sluggish in the bumps and trees. If Dynastar made these in a 168, I might have bought them (but only if I hadn't tried the Kastles).
Salomon Enduro 85, 163cm, 170cm:
These are STIFF. Great at speed, decent float (esp 170s obviously), fairly nimble, but a real bear in the bumps, which was the dealbreaker for me.
After trying everything First Run had, I still wasn't totally into any of the choices, so I went over to Equipe to give the Kastle's a shot.
Kastle MX78, 168cm:
WOW. These blow everything else I tried out of the water. Simultaneously smooth-feeling while maintaining quite severe feedback to bad skiing, stable without being overly stiff, and LIGHT. The edge hold was nothing short of outrageous compared to the other skis. Took some getting used to in the bumps (because of the edge hold), but I figured them out before long. I have never really liked groomers and spend 80% of my time in the moguls and trees, but these skis have made groomers exciting for me for the first time since I learned how to do bumps. They have also improved my form. You have to ski these in the front seat to get good edge hold, which I like. They also don't look like crap, a quality that is becoming rarer every season.
Kastle MX88, 168cm:
Similar to the 78, but slightly slower edge-to-edge, a bit stiffer, and bit more stable. The first of those was what tipped me toward the 78s. If I skied out West, I might consider these as a front-side half.
I bought the MX78s, for obvious reasons. They really are worth the money, especially as an East Coast 1-ski quiver, which they are for me. In hindsight, I probably should have tried some more 75-80mm underfoot skis, but I really can't conceive of anything being better than the MX78s.