I've only trialled this system recently, but my current results are:

1 Win

2 Partial Wins (basically a loss with how much you get back)

3 Losses

All these payments were fraudulent (a user doing credit card testing) and disputed by foreign banks (Thailand, Malaysia, Brazil). I think these cases are much harder to win, because the actual card holder is technically in the right to request the money back on their stolen card for a transaction they didn't do.

Much better than my previous results of just accepting each dispute though :)