Tyres - if the Br*mpt*n accepts them so will the Mezzo/Ori. Out with the boys yesterday, it was noticable that the Mezzo with its high pressure Kojak slicks, rolled further without pedalling than a couple of 20" bikes fitted with Schwalbe Marathons. (The 20" bikes had hub gears though.) I don't know what the bikes now come with, but the original Mezzo tyres were 85 psi medium pressure tyres. I think the high pressure tyres address the increased rolling resistance of 16" rubber.

See this pic for side-by-side images. The Ori/Mezzo fold is slightly taller and wider, but will mostly fit where the B*** fits. I keep mine in the trunk of my city car. Both weigh about the same.

A rear wheel flat or tyre change can be fixed in minutes on the Mezzo/Ori by the way, as opposed to the unseemly and lengthy fildding needed at the rear end of the B.