No experience with the CCAT and not for K, but FWIW - DD9 was tested in 2nd on CogAT and scored a composite 99%. Her WISC IV a year or so later was above 99.9%, with relative strengths mirroring the CogAT results (highest Verbal on CogAT/VCI on WISC).
I have not heard as many stories about the CogAT overidentifying kiddos, as I have underidentifying gifted kiddos (it seems to miss many here who later have a high WISC score). I tend to think that a high CogAT score, then, is usually not accidental.
