@KaW~KaW:
I think Momo's DF is a failure in the aspect of not being able to control when he transforms.
Iv been analyzing the whole DF failure thing and Iv got a few theories that might be true.
1.) If Vegapunk's ADF was a failure then why would he encase it in glass. Failures get thrown away, not kept on a pedestal. I think CC told every one that the DF was a failure because Vegapunk made it. If it was a failure then Momo wouldn't have turned back to human form. We don't know the difficulty level for a child to change forms as new zoan user is.
2.) CC is a 3rd class scientist as proven from the beginning(Helium balloons to move around). He stole Vegapunks research and made it his own and created the smile fruits. But all of this still doesnt explain why Momo saw an image of DD, my first thought was maybe the DF was tweeked the way DD wanted.