Just wanted to chime in that I saw that J Crew bag today in store. It is a gorgeous color. I am wishing I had noticed the RM in store one so I could have mentally compared.
The straps on the JC bag were definitely thin and stiff (the whole bag was stiff and very structured). It did have multiple interior pockets that could be useful. That one little pocket on the outside didn't bother me but I'm sure what someone would use it for- and I would be worried about it catching and breaking the snap. The one thing that struck me is that it might not be big enough at the opening for your things. There are 2 snaps at the tops sides that expand the opening but not sure if that is something you would need or want to deal with everytime you were to use your bag.
I did really like the RM one on you when stuffed with your own stuff. It might just be a good test to see what your threshold for soft vs structure is (although a somewhat pricey test).
Hope this helps (but maybe you've already decided). But it was good to go in because they are going to be closing until October for a remodel!

Muffin, thank you so much for this thorough review -- SO helpful.

It sounds as if the J. Crew one would be super useful and "easy" for me in the sense that it would be similar to other bags that have worked for me in the past. But I think I am going to keep the Minkoff. I played around with it a bit today and yesterday and it seemed to be working. I'll get a bag organizer for it to make things a little less lost inside -- if I need to. And this way I will learn how I feel about unstructured bags, I guess. It's worth a try at the sale price.

Yes, please do keep the Minkoff, Suz! I love seeing it on your arm--the rich leather just seems to glow. So chic, and just different enough to underscore your new silver look. If it works for you in every other way, I think you'll be glad you did.

So happy you're keeping the Minkoff bag. I did some looking around for that color online and saw nothing better. My guess is that you'll be very happy with it. I have several of her bags and the quality is great.