Most research is wrong or rather so skewed and misinterpreted as to be useless or even dangerous to the corporate decision-making process. New Coke was the result of research
But putting that aside, there is a big difference between brands and categories, which is what the CHR, AA, AAC and other labels are. Radio hangs a thousand labels on formats, but when you tune across the dial it's the same old thing every where you go with differences between many categories so subtle as to be meaningless except to deluded programmers who still think the hot clock is the key to success.
And "Why is Star beating Sophie?" - because Sophie was designed to be a format, not an entertaining radio station.
And why is Star, called Star? - because of Jeff and Jer who had been big stars at "Star 100". Had that not been the case, My94.1 (man was that a lame name) would not be Star today, but it would still be an entertaining radio station.
The Hot AC, CHR labels are all the legacy of the era when some fool gave radio program directors access to computers and they decided they could create formulas and then have the computer plug music into those formulas, spit out a play list and voila, success! If it didn't work, then you programmed in a different formula.
With few exceptions radio is so driven by formulas that the lack of local talent hardly shows. I'm not a big fan of DS&C but I've been listening to them a lot lately just to get a better feel for what they do. One thing they don't do that seemingly every other morning show does is the tiresome cliche gossip news/American Idol chitchat/celebrity dirt stuff. That has become such a crutch for morning shows who apparently have decided that show prep simply means watching the E-channel and "reality TV." No wonder so many stations are opting for Ryan Seacrest: he can do the entertainment news much cheaper than a studio full of local yokels, plus Ryan's got the brand recognition to boot.