But the combination of the OGS rating system with the handicap system actually seems to be pretty solid, as it keeps the winrate of Black at around 43% in games with less than 5 stones of handicap. The statistics (or some statistics) are discussed here. According to that post, 43% is also the winrate produced by the handicap/rating system the EGF adopts.
And in this very topic (EDIT: no longer after the fork), reply 42, I proposed two conjectures as to why that might be the case 