You asked about all mountain skis "for use in the crud that is SE skiing". Unfortunately, there are lots of types of "crud" around here.
Other geographic areas also get variable conditions, but we certainly get our fair share of them. You might have perfect groomers one day, then it rains. While raining, the conditions might still be quite good until night fall when the temps drop below freezing and the hill turns either to a tilted ice skating rink or a maze of ruts and coral reef. Another day, you might be skiing in a 6-12 inches of sopping wet, slurpy like new snow more typical of lower altitudes at Whistler. Last spring at Whitetail, I have postholed to a depth of 18" into snow that was rotted (ie, slurpy like) and melting fast.
Because of this variability, IMHO, the real dilema facing skiers around here is that the type of skis that are optimal when its groomed are nothing like the best skis for rock hard ice, which are nothing like the skis that are optimal when its deep slop. At least there is one set of conditions that we don't have to worry about: Cold dry powder.
IMHO, most modern groomer skis can be skied well on ice and icy crud if they are sharp and the pilot has the skills. I assume you probably already have a pair of skis like this, so I'm not going to try to deal with this category. Instead I'll focus on skis for soft crud.
There is nothing special about our soft crud, so skis that would be good for soft crud anywhere in the world would be fine to use around here. For example, about the only differences between crud here and in the PNW is that our runs are much more narrow and shorter, so we need to err on the side of shorter turning radius boards, while in the PNW, they regularly get deeper wet snow dumps, so they can make use of powder ski like widths in their crud.
IMHO, how wide to go is mostly determined by your weight. See this table to get an idea: Equivalent Float Chart
. At 170 lbs, something in the high 70's (mm) or low 80's wide underfoot would probably work just fine for you.
OTOH, how stiff to go is determined both by your weight and speed/ability. Go stiffer if you like to make long radius arcs through pushpiles of wet spring slop at Mach 7. Go softer if you like to always feel totally in control through lots of turns around the pushpiles. Don't go too soft for your weight (even if you are very timid) or your skis will be too twitchy in irregular crud. As an intermediate, to give you a reference, skis like the g4/ax4 (82 mm underfoot) will definitely be too stiff for you. 10ex/Rex's (83 mm) are a bit softer, but probably still too stiff unless you are really agressive. I won't try to make any specific recommendations, but take a look at old gear discussions here as well as all the 75-85 mm models listed on Peter Keelty's site, www.ts2003.com
. These days, there are lots of skis with moderate flex in this width range.
With respect to length, aim for something around 170-175 cm if you are considering a 75-80 mm wide ski. You can go as short as 165-170 cm if you go fatter, say, above 80 mm wide. Don't go under 165 on any ski for crud - you lose too much fore aft stability, and the ski just doesn't lay on enough snow at one time to do a good job averaging out the irregularities. Personally, if I were you, I would aim for a moderate flexing 170 that was around 80-85 mm wide. If you go fatter, the ride on soft crud will be smoother, but it will start to feel noticeably "fat" - high swing weight for pivoted turns, slower to edge, etc. If these things don't bother you in a crud-specific ski, IMHO, then there is absolutely nothing wrong with going up as high as 90 mm wide, but you will lose groomer performance.
Tom / PM