Unless you replaced the fork to have a 100mm OLD, you cannot mount a SON Delux hub dynamo on a Brompton that has a fork with 74mm OLD. Its probably a SON XS or SON XS New (its what I have with also Edelux II and SON rear light).

I saw other comparison tests that show that SP dynamo hub are very good and close to SON. So, I think that replacing the SP SD-8 by a SON XS doesn't bring any noticeable benefit.

For the front light, its different, the SON Edelux II is much better and I like its auto mode with the light sensor that automatically put the light on in tunnels...

For the rear, the BUMM My is very small and powerful.