I really think it depends on who the opposition is. When we play a team like West Brom we will use Yaya as the pivot. I think when we play strong sides who press well like Spurs we will may play a midfield 2 with Dihno and Yaya or Gundogan. I don't feel comfortable with Gundogan as a single pivot though. I've seen him give the ball away when pressured. I can't remember which game. It may have been against Barca away. I also think you need some height when balls are in the air in the midfield.
Gundogan doesn't give the ball away, he just doesn't, he's nearly as good as Silva at positioning his body to protect the ball and make his next pass as simple as possible. You clearly haven't seen enough of him.