The 4-2-3-1 without Del Piero is working very well.
The 4-3-1-2 without Del Piero doesn't work.
I have no doubts that a 4-3-1-2 WITH Del Piero will sooner or later start working well, at least as well as the 4-2-3-1 without Ale.
Now, it might take some time, some 3-5 matches until the 4-3-1-2 with Ale starts working (Diego and Ale will need some time to gel). These 3-5 matches might mean more lost points and eventually missing out on the scudetto.
I'll take the risk. Many might lose the patience if we lose points with the 4-3-1-2, but i'll still take the risk and play the 4-3-1-2 with Diego and Ale.
I'd do it because it offers something that might prove huge in the CL and next year in Italy. After a long long looong time it will give us two equally deadly formations that we can use depending on the opponent, or sometimes even in the same match. The opponents won't know what to expect from us, as they did from 2004 till now.
Being able to use different formations and having the players for that was one of the reasons why Lippi and Italy won in 2006.
Capello couldn't do it, Ranieri couldn't do it. We were bad in Europe and suffered in Italy too with Ranieri.
If Ferrara can do it, then we can achieve big things. Taking a risk in order to achieve that, is a risk i'm willing to take.
And then again, there is a chance that the 4-3-1-2 with Ale, will start working instantly. In that case it's even better.