There's nothing wrong with 3 defs, narrow or wide, imo. But as Khris hints at the more critical a players role is the more fragile things are if they don't perform. When they do perform they can be immense. Balanced formations are more forgiving but can lack the punch in circumstances where specialists might work better. But roll the dice and anything is possible
PS. Just remember that no matter how much you convince yourself how great your players are that most T11 games are probably more like 2 pub/non-league teams than el Classico. So if a guy fails, give him a hug before you shoot him. Hmm, I'm rambling again..."Nurse!