I find ice grading "systems" of little use - have climbed classics rated WI5 in WI3 conditions, and conversely have been scared shitless on WI3 in other conditions. I use a three level rating system:
WI-fun -- self explanatory
WI-whine -- my lead standard since 1972
WI-no -- cant get up it anyway, so doesn't matter
-Haireball
Thats good shit.
I use the absolutely no, give it hell, and not a problem for my lead ratings. All about conditions!.