Lean or rich are tuning issues that essentially all carbs need to be correct for a given application. The original jetting may be lean for Carter/Edelbrock carbs, but that is just a metering rod or jet away. My experience with Carters is great. My 340 FB FS was no faster with a 750 Holley than the original AVS, but the AVS got far better fuel economy than the Holley.
What is more of an issue today is the quality of fuel. Ethanol eats the inside of carbs if let to sit for any length of time, and ethanol destroys Viton seals causing flooding. This can happen to any carb. Ethanol also eats the plating on steel gas tanks putting rust and oxides into the fuel system, also leading to leaks.
For us, the sad thing is, ethanol does nothing for emissions or performance unless you design the whole system to be compatible with it.
