I like the IDf's(because I have them), they are easy to tune, my set up was all new, with excellent linkage, Each carb had the same idle, main, air corrector and emulsifier, they were all wrong for my set up, but the car ran and it was a starting place. The main advantage with IDA's that I can see is the idle mixture screws are on the inside of the carbs, not next to the valve cover, they are difficult to adjust when the engine is warmish. Fuel flow is very important to Webers and the stock fuel pumps on my CAV were not up to the job. I installed some Carter rotary pumps and now the fuel pressure is consistent.
In any event, they run like fuel injection and look sound cool as hell!