If I was just using as daypack I would stick with the ultra. Personally I see no reason to go smaller than the 3000. Just the bag is the difference and its minimal. Yes when packing out 80+ pounds of game it would be nicer to have the icon pro heavier belt and straps but is it worth having them all the time when your just packing a sandwich , kill kit, water and jacket? If you want to pack your camp then definitely icon pro suspension. You could get by with the 3000 bag though its snug for camping. The 1850 no way. I started with ultra 3000, packed a couple yukon moose out with it over 5 miles worked fine. I did find the belt more comfortable over a jacket around my waist so when icon pro suspension came on sale for $93 I picked one up for possible long packs or camping. For day use Im sticking with the comfortable and minimalist ultra throughout.