I'm 6'1'', 220 (hopefully less by ski season, but even my "fighting weight" hasn't been below two bills since High School).
I ski about 30 or so days a year. Mostly East Coast (Sunday River) with about a week out west somewhere in there.
I've been putting in 30 or so days a year for quite a while, and I did some organized racing before that. However, there was a little post college expiremental phase with snowboarding.
Using the standard rating system, I'd say I'm at least an 8 and most likely a 9.
I'm aggressive and seek out difficult lines. While I enjoy screaming down a groomer and take an occasional lap through the park, I'm in the lift line before the lifts are turning on a powder day, and I'm much happier off piste (when the East Coast snow gods smile upon us) and love the trees and steeps.
So, I'd think I should be in the ~315 bsl shell as well. My current boots are 100 flex and a 316 bsl.
On related note, I got sick of sitting in traffic on the way to Cape Cod last Friday and hopped into a ski shop in the area to see if they had anything that fit well. I tried the Salomon Impact 10 which was too sloppy around my ankle/heel, Nordica Ace of Spades which the 28 shell was too big and they didn't have a 27 shell, and the Tecnica Agent 110 in a 27.5 which fit well enough, but was still a little too sloppy in the ankle/heel and was not stiff enough.
However, it was funny as the kid working there insisted on bring me 28 shells after measuring my foot.
"Mister, you don't want a 27.5, that's a size too small."
"Just bring the 27 shell"
"But that's a size too small"
"Hey, it's not my fault you guys sell ski boots that are too big, now let's see some 27s"