I think the style of linkage would depend on the carb size. Three small units should work together as one large equally spaced single carb. If the carbs are big enough to run just on the center one alone, then progressive linkage would be a better option. The engine would have better air flow at high rpm to accept the added end carbs input.
From what I have found on my engine (250 ci) the multi-carb setups do run slightly better. All around smoother running, but fuel mileage is about the same, starting about the same, and performance about the same, as my OEM carb.
I run them for the challenge of getting them right and perfectly tuned. For those not really into tuning and testing, single carbs are the way to go.
Joe
