Anyone still looking at luggage I would highly recommend Kriega, I use a US-20 or my US-10 on a daily basis and I have done long trips with a 20L+2x10L setup. All clip together in seconds, Can sling them over your shoulder with tuck away straps or mount on top of passenger seat, sling over rear seat or attach pannier style.
Additional plates available for heavier loads/bigger bags to modify bike and fitments. Possibilities and combinations are endless and every bag they produce is compatible with every other bag and fitments. Clever designs on straps zips etc so everything has places to tuck away when not in use.
I can vouch for waterproofing and durability on them too. Still good as new after a year of throwing them about on daily basis.
PICS:
What I have:
Pannier style:
The range:
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