I ended up getting the bag I'd asked about in this post:
I'm pretty happy with it. It's well made, has nice details (such as little hoods for the zipper pulls to prevent them from flapping in the...
Unfortunately, I bought 2 of these and the store didn't want to take the other one back. So, I need to get rid of it. $50 plus shipping. It's still new in the box. This is a pic from this forum (not mine).
Having realized that my stuffed-full 34 liter backpack will probably paralyze me if I ever go down, I have started looking for on-bike luggage to replace it.
I typically commute with the following:
expandable duffel for my ATGATT riding gear once I get off the bike