I use an S&S case for my Brompton. Needed to adjust the handlebars slightly to get it down to 10" thick, but it works like a champ. I don't need to remove my extended seat post like I would for the b-w case, as I imagine handling a folded Brompton without the seat post to hold it all together might be very much like wrestling a spastic jellyfish. Even better, if I ever do get that Surly Travelers Check then one suitcase fits every occasion.

And one more thing: the sturdy b-w case puts you right at the 50# weight limit for most airlines if you have enough goodies on your Brompton. My S6 with every accessory available still comes in 5# light, packing materials included.

Please let us know what you find in the course of your research, it's all useful info to me.