I reckon dynamo on Brompton is a good idea, and this reason is a part of it. Like the toolkit and the pump, means you can pick up the Brompton knowing that everything you need is there without having to collate bits and pieces from other bags .
Ive got SON but with the SP setup the weight difference from reflector only is something like 250g, so barely worth thinking about.
You’ll want to upgrade the front lamp as the standard one is very disappointing.
Carradice bag you need the appropriate luggage frame to fit in the bag, then it clips onto the block same as an official Brompton bag.