V brake levers won't have the correct amount of cable pull to work with the brompton calipers.
was an extreme proposal. the V lever pulls a lot of cable ,
so the lever won't swing far thru its range of motion ,
so it will feel harder.
A V brake caliper is a long [type2] lever so needs a lot of cable movement to pull it a short distance at the work end of it's length.
I fit cantilever pull levers on mine, the little S bend in the lever
had some Dia Compe PC700 fwiw on hand..
keeps my finger from sliding too close to the lever pivot.
since I'm Reaching around the bar end of the Ergon grip/bar-end combination.