The motor builders will set the carbuerator for the fuel delivery curve that is right for the way the set up their motors. For driveability and maximum power the carb needs to be rich on the bottom and lean-out as the RPMs rise.
So a motor builder will set the pop-off pressure, fulcrum height and suggest needle settings according to experience or on the dyno.
Certain carbs will just flow more air and therfore they make more power but all can be made to run well. Some motor builders will set/adjust the throttle stop position for WOT at the point where the air flow is at its maximum.
I find that regular maintenance like daily disassembly and cleaning keeps it running good and reliably. Also I recommend a good fuel filter as debris really screws with the operation of a pumper style carbuerator