If I'm not mistaken (it would not be the first time), around 1968 - '69 Rochester could not keep up with the volume requested from GM. So, GM had the Carter Corporation produce some Quadrajets to keep up with the demand.
I had heard the Quadrajets (when setup correctly) were better on steep inclines and rough trails due to the float/bowl design.
Holley's are great carburetors. I'm not opposed to changing. I was just hoping to save some money. I've found it's extremely difficult, though, to find anyone that has much experience with the Quadrajets.