I skied the back-country around Lake Louise on Saturday, and the resort on Sunday.
Spring has finally hit the Canadian Rockies. Temps at the base of Louise were +5c on Saturday.....with a lot of sun, and +4 on Sunday with more cloud. For both days, solar aspects were in the melt-freeze cycle, but it took a bit longer to get the melt on Sunday. New snow (although not super deep) made the freeze phase surprisingly enjoyable.
We found dry winter snow on Polar Aspects with true North aspects like ER6 and Pipestone Bowl having very light snow. Northeast and Northwest facing slopes were also very wintry.
I chose my narrow skis on Sunday (98mm bonafides) and was happy with my choice. Liz went wider with her Sheeva 11s and seemed to think they were okay too.
I don't think you can go wrong with either choice. I like a 100mmish ski as a daily driver for this region...so if I was in your shoes I would probably bring the 105s, but if you prefer the 85, I doubt you will be needing any float.