all i can say is that on my hobbit the 70cc malossi kit with the motomatic hobbit pipe and the stock 12mm keihin was great. but, i put the 21 PHBG and the fucking thing screams now. its insane the difference that carb made.
plus, i was running a 16 PHBG on my SSXL with a 70cc pollini, and when i finally upgraded to a 19 it was a world of difference.
i'm not saying you arent right on some levels, i still run a 16.16SHA on my magnum and love it. i'm just saying that you cant really generalize about every carb/kit/pipe combination, thats all.