Thanks for all the great feedback.
Neal, I am keen to see those graphs please. Without wandering into the murky depths of the eternal 250 vs 300 debate, I am at least going to give the 300 a try! A friend here swapped a 600 for a 300 kitted NSR that was poorly setup by someone who knew little about smokers (yeah, I know, thats why he bought a 300 kit haha!). Anyway he did a recent trackday here (I think that NSR Tom was there too?) and for someone who used to race a HRC F3 kitted NSR and an RS250, he was pretty impressed with it. The problem with racing them here is that you are up against 3 cylinder, 450cc GSXR600s, 80hp SV650s and fast tigcraft 450 singles and 550 twins..
I still dont know what to do about the HRC MC21 carbs, perhaps I just get them and try them out...