Nice write-up - I'm using the Urban 550 and I love it. It does get a little hot after a while.

- There are plenty of sub-$100 video cameras and it would depend on whether you'll want a viewfinder. That seemed like a no-brainer until I read the review (and bought) the Mobius Camera. It's tiny, simple to use, works well, but the biggest downside might be adjusting it so your videos aren't 80% sky or ground.

- I use the C-bag most of the time and I'd argue it's by far the most useful all-rounder among all the Brompton bags. I love the basket too but I do think it's overpriced for what you get. I have the T-bag as well but it's definitely less flexible for everyday use. If I had to get another bag, I will go with the Mini-O as it's waterproof and not-too-small. Price-wise however, is a different matter.

- Most people find the original saddle intolerable but I'm not one of them - to me they're fine. Yet somehow I ended up getting a Brooks B17, B72 and B67 for my 2 Bromptons. They're great saddles and looks fantastic. IMO I haven't gotten them fully worn in but I love the width of the B67 and B72 (my butt is average size). The B17 is kinda meh.

Personally carrying it by the seat never felt right to me. The weight was concentrated too much to the front and it felt more tiring to do so. I usually have the folded bike facing backwards and lift it by the top tube. That just feels more right to me.