Steve, I previously ran the GX carbs on my car and people offered up all sorts of "hot tips" for setting them up. I tried one or two, mostly to do with oil in the dash pots and went back to the factory settings. Absolutely nothing wrong with them, they would still be on the car if it weren't for the deal I got on the FCR carbs.
We also used the standard CV carbs on our Yamaha powered sports racer and the only issue was one of fuel slosh/starvation due to high G loads
Now I will have to disagree with the FCR carb; it is the standard carb on my Beta 520 and you can lug the bike or if you're stupid whack the throttle open like a gorilla. All the magazine tests also raved about how well the carbs worked. Same goes for the 1200 it will motor around the pits without protest and pull from as low as 2500 rpms with a 278 degree cam. When I was running the GX cam in the motor with the FCR carbs it would have been perfectly streetable. The only issue I ever had with drivability was due to 286 degree cam which had a lot of overlap; it was unhappy below 4500 rpms, it was even a pain to put on the trailer. There are a couple of idiosyncratic things with the FCRs as you mentioned but I simply jetted accordingly.
One thing I will totally agree with is that carbs are not as simple as people think. I am also amazed at what people will tolerate on all types of carbs. My Ford F350 struggled to get though smog, the needles started raising up fully at fairly low rpms causing it to run rich. Simply changing the springs cured the smog issue and the gas mileage went from 10mpg to 12mpg.

Tom