Originally I was going to get CR29s, but there were too many reports of them sucking. The common theme was that the carbs were too big for the 550 and would go way lean below 7k rpm. The fact that most people run them with pod filters doesn't help, but still.....
Sudco recommends CR29s for the 550, and probably because they're the only US importer, everyone else recommends the same thing. Except for Keihin. You know, the company that actually makes the carbs. They recommend the 26s for mildly built 550. For a full-on race motor on a racetrack, they do recommend going one size larger to the 29s. For a totally stock 550 they recommend going one size smaller. Or would, if that size existed.
But anyway, that agrees with what the sohcforumites were saying, so I bought a set of 26s. I do already have a set of CV carbs that one guy said worked well; good performace, terrible fuel economy. But, it seemed like a lot of potential screwing around to get them working right. I'd rather spend a week screwing around with jetting than a month.