I find 185 is a good length for everything. Shorter is easier in the tight trees though. My 191's are big powder boards but have no trouble on groomers..just not solid ice. Long skis on groomers work great..see how long race skis are.
I've read very good things about the Head Kore line. I bought the 117's in 191 length . The 93 width got very good reviews for all conditions.
Go slug!
I am about to pull the string on a pair of Kore 93's along with a pair of 117's for powder days. Will probably go 180 for the 93's and 191 for the 117's.