LOVE my backpacks!
I have a lightweight for the days I don't need to carry my laptop (usually Tues, Wed & Thurs) and a super-duty Zixtro for when I do.
I don't like the way paniers change my bike's handling; when the load is on my back I feel like have more control over the weight.
I suppose you can get used to anything if you use it enough...
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Today, I believe my jurisdiction ends here...