I got the extra padding in my bagaboo workhorse messenger for pretty much those exact reasons (every week carry several of tons of booze up 3 flights of stairs solo (sans bag obviously), on top of the carrying a several kilos daily every which way), but it kept digging in my back, until i loosened the compression straps... oh happy days. I can carry it to capacity over one shoulder without any back/neck/shoulder pain. To be honest I've got the extra shoulder strap, but still haven't found the need to use it (even carrying a case and a half of cans).
I got the extra padding in my bagaboo workhorse messenger for pretty much those exact reasons (every week carry several of tons of booze up 3 flights of stairs solo (sans bag obviously), on top of the carrying a several kilos daily every which way), but it kept digging in my back, until i loosened the compression straps... oh happy days. I can carry it to capacity over one shoulder without any back/neck/shoulder pain. To be honest I've got the extra shoulder strap, but still haven't found the need to use it (even carrying a case and a half of cans).