All the stuff I have read on friction seems to say that the

major factors in friction are the coefficient of friction

(slickness or roughness) and the "normal" force. On tires the

normal force would be the weight of the car in toto, or for each

tire, the portion of the weight supported by each wheel.

Surface area is a minor consideration unless a LOT of heat is

generated by the slippage (and then the larger the area, the

lower the temperature.)

I would say there is NO benefit to grinding your crank or putting

in smaller bearings unless maybe you are doing research. If you

grind the crank in such a way as to reduce the diameter, you are

also reducing the strength of the crank and raising the stresses

in it.

In summary I would say the B20 has an admirable crankshaft design.

I think that the likelihood of improving it by reducing bearing

area is vanishingly small. Same goes for the B30. My first one

had NO measurable wear on either the crank or the bearing inserts

after 204,000 miles.