Bill,
the rear spacing is 115 I think,so you’d have to spread the rear triangle for an alfine hub.
advantage of the alfine is that having a disc mount, with some superglue and a spoon and you could have a disc brake on the back..
I used the alfine crankset,it was on offer at crc,and already had a bashguard,and the right size chainring.
the brompton shop told me I’d need a special bb,with spacers to get a good chainline,that’s what they do on the ones they fit.
the chainline seems only 1mm off so it’s not a problem.
the highest bars with a 25.4 clamp were the ns chemical bars with 3″ rise.
the m bars are 6″ rise so its a bit lower than the s-bar version now.there’s some electra bars with 4″ rise but were double the price.
the fold is fine.as they’re lower,they end up farther up when folded.so its the same size folded.
bars and cranks make it feel much stiffer and stable.
really do recommend it.
best thing for the brakes I found was to use v brake pads,instead of road ones.that helped a lot,as did shimano flat bar levers and fitting noodles to improve the routing.
and those mks ezy pedals.stock are crap.
hope this helps.
I’ll post a pic later if possible.