What is dubious about the opinion that on the balance of probabilities Madeleine was abducted? On the balance of probabilities what do you think is more likely?
In the context in which it is being bandied about "Balance of Probablities" is a legal concept; see davels earlier post in this thread if you are thinking it was something else we are discussing wrt to balance of probablities.
How balance of probablities works in the legal sense is that evidence is presented by both sides to the court for a judgement on where the balance lies. Thus far it hasn't been presented at court therefore in a legal sense no one on this forum can make the presumption that the legal balance lays one way or another.
As we don't have all the evidence to hand, as little as 17% if you believe some posts, we on this forum are in no position to weigh the evidence as would be required.
You are asking me to speculate which way the balance lies, which as you have pointed out recently is not permissible on this forum.
Just to make that clear:
I don't know what happened any more than you or this entire forum do.