The Three knights game is rare and occurs in less than 1 in 100 games. From the data, you can expect that White will have a 48.73% chance of winning, while Black should have a 51.27% chance of winning. Even though most players rarely see this opening, (so you can catch them off guard), the edge that Black has is small (less than 2%). It is probably not worth it to study this variation, since as Black, the edge you gain isn't that great.