I am 6-2" and Dahon bikes, even the ones rated for someone my height run over an inch small in the leg extension department. Brompton says rider weight limit of 245#, and they offer the extension seat post.

I ride where there are hills, gears are a gotta unless you plan on walking...a lot. FWIW my regular Raleigh 3 speed has a 24t cog on the rear and I still have a couple that I have to walk up.

Aaron