Not being privy to the inner workings, I don’t know how much StAs uses the extra info- what is clear is that they give GPA guidelines, talk about ECs, flexibility, etc, and are fluent in American college app-speak. I haven’t seen any breakout, but would be interested to see a breakout of students applying via UCAS and CommonApp.
@Capricancer1, you are right that both grad schools & big companies do milk runs through the upper end unis, but I thought that StAs was a bit more active in organizing Skype interviews and things? I may be either misinformed or mis-remembering (both are plausible!).