I have not yet sent anything Epsom to the spa, but I do believe they can't do much with scuffed Epsom corners. I didn't have any issues (nor with my Kelly 28 in Epsom) and at the time, I was in a city where I was 100% walking or using the subway. The corners on both were fine. Honestly, my own kids and husband are usually the only ones knocking into my bigger bags.
The Epsom B35 even got soaked in the rain a few times and was completely fine.
I did find that B35 Epsom retourné does crease in weird ways though. I think the previous owner never used it and stored it laying down for years since it seemed take on a kind of curved shape of the tissue that comes in the box. I know a lot of people say storing Birkins laying down with the box and tissue is best, but I don't like it. Even with my Clemence 30- the back zipper pocket started showing through the leather when storing it laying down.
This thread got me looking at 35s again and I see the exact one (in terms of color and PHW) on
Fashionphile that I had years ago, but at twice the price.

Should have held on to it!