In all honesty, I'm not that far off.
If he's a young ripper who laps the tram at BS or Jackson, or constantly is hiking, he's going to want something over 110.
If he's a resort skier, who skis more groomers and all over the mountain...then you can go with something not as large waisted.
I don't know many people at big sky who lap Headwaters, the Tram, and Challenger that ski anything less than a 110. And that includes a 73 year old man.
We were talking about one ski for a whole season. Most seasons I think that you would be better off with a ski just under 100 for a one ski quiver at JH. I say this after skiing here for 25 seasons. Of course I'm old and I suck and I don't care what some hatchling thinks about my skis or my skiing. I will usually listen to them when they catch up at the bottom. If you are spending most of your time hiking something over 110 "might" be better, but you give up a lot inbounds. It can also be observed that there are a lot of people on skis over 110 who really don't ski very well. It's about how much fun you are having, so if a fat ski makes you happy go for it. I've learned that part of being a professional is not imposing my "free" advice on people who don't ask for it. It amuses me to listen to people talk in the Tram line and then see them ski.
When we start talking about having several skis, then something over 110 definitely has it's place and will get used if you ski a lot of days. I have several skis that are over 110 and bring them out on big days. I can only keep three pairs of skis at the mountain and I hate carrying gear on the bus. Last season I never skied anything wider than my 106mm Soul7 except for a few times that I demoed. I spend most of my time on the upper mountain teaching advanced students. I ski a lot of days, I generally ski all day, and I try to always keep it moving. I have never felt like I needed a ski that was much wider than 110mm and haven't really liked the feel of any ski wider than 120mm even in deep snow.