In my opinion there is a difference between trained players and others, but it has become quite minimal overtime... I would not go for crazy white skills or mutants anymore in todays game, it is not worth when boost lab players are almost as effective.
But how old is the player you want to train? If he is still young, it is worth to go with a more expensive plan and raise as few grey skills as possible. It makes it easier later to keep his overall quality high when he gets older.