I hope the padding is good enough on that sling bag....from my personal experience, a sling bag (with bad padding) on a long walking photo trip will give you sore shoulder the next day. If the padding is not enough, you may want to consider a better padding to "add on".
My previous "long dist" (Skygarden -> MBS -> Bugis) photo shooting trip landed me with a sore shoulder the following day.
My previous "long dist" (Skygarden -> MBS -> Bugis) photo shooting trip landed me with a sore shoulder the following day.