Problem with this is defining a FC (in osu!standard at least).
Does it have to be max combo? In that case, Cookiezi's Big Black would not be considered a FC.
As an extension of that: How many slider ends are you allowed to miss for a FC?
Is a score 2 below max combo that broke combo on the very last slider but still scored an S considered a FC? Since that can easily be a higher combo than a non-sliderbreak score with missed slider ends.
And the fact that # of sliderbreaks is not currently stored as far as I know, so this would probably add quite a bit of server load and old scores can't be properly analysed either (since there's no way to know if they sliderbroke at the end or just missed a few slider ends).