-
I always commuted with a bag, a courier bag until recent years as my smashed up collarbone didn't get along with straps and I hated panniers - I like to get off the bike with my stuff.
But doing longer rides I'd try to avoid backpacks unless strictly necessary. I've got my Camelbak here from Oz but haven't used it once. I may test it out for MTBing once I get my bike built - being able to drink from the pack when you want both hands on the bars seems like a pretty big advantage compared to trying to grab bottles on tech terrain. Like most things I guess you'd get used to it.
I've not even got warmed up yet.
https://www.youtube.com/watch?v=WtcnmzEAWe8