sorry, no info on that. I am trying to decide on a rack for my own Brompton. A site/group dedicated to Brompton only could be a better place to ask.

Personally I have never heard of a Brompton rear rack that broke in regular use. I would think that if it happens it is becouse bike was dropped or stuff dropped on the bike (like in air travel). The stays of the rack is not super strong but they are easy to replace.

There is also at least one TI option for rear rack. Not sure about strenght but should be lighter.

A front rack like the one you linked to is also sold by "bikegang" on ebay. You`ll find him in this forum too.

Keep us updated, especially if you buy something "not standard".

There is TI luggageblocks you can buy for the B too. Not sure about strenght compared to the nylon one. Keeping the bolts tight is important to keep flex at a minimum and avoid material fatigue in the bolts. We have heard of bolts breaking