Nor did I mean switching to Mikunis or other carbs is wrong, it's just that as you say,there is no need to!
In my own case the one set of Mikunis I have came with on the bike, so I was interested to see how it ran in comparison to my Concentric equipped Vincent. After all of the strong advice I had been given by my fellow club members who insist that Amal Concentrics are crappy carbs that will not meter the gas flow properly at anything under full throttle, I expected the Mikunis to give superior performance, easier starting and smoother running than my Concentric equipped bike.
One fellow was quite insistent about my need to throw away the Concentrics as part of what he claimed I needed to do in order to make my Vincent "make power" like he claimed his did. His is heavily modified with 9.4 to one pistons, Lightining cams, Harley Screaming Eagle ignition, ported intakes and exhausts, large diameter headers, Supertrapp exhaust, huge twin 36 MM flat slide Mikunis, five speed Quaife and some other stuff I have forgotten.
Every time we met he would start in on my need to "spend some money on the bike and make it competitive".
Along with several other Vincents, we ended up riding together on a 3.000 mile trip to the southern US and home. In Idaho on a six mile long 10% grade he took off on his hotrod Vincent, passing the Group leader. We were both two up with gear, but my bike was loaded about 50 pounds more heavily than his. I decided to give chase and to my surprise managed to catch him and pass! He damn near fell of his bike when we cam up alongside. He later claimed that he could have dropped one more gear and caught us, but I think not! He said he didn't want to frighten his wife, pure BS., with his riding (fast)he had her scared out of her wits most of the time anyway!
Six months later we got into again at a Rally in central washington.
Again he passed our ride leader and I gave chase. This time we were solo and the speeds were greater. I caught him at something over 100 mph and backed off just a little to stay alongside, then opened the throttle and slowly pulled away!
He no longer tells me that I need to spend money on the bike to "make power" or that I should junk my carbs!
Initially the Mikuni equipped bike ran poorly at high RPMs but with several main jet changes that is no longer a problem. It runs just fine, as well as the other bikes but no better, but is sometimes difficult to start whereas the others are not. I remain uncovinced that the Mikuni is a better carb for these bikes, other than the slide, which as you say can be rectified by sleeving.