All of those scenarios are garbage.
If we want to use Pirlo effectively, we should use the 4-3-3. There's no sense in having Pastore have to worry about coming back to defend, as that's just going to ruin his effectiveness. Plus Pirlo likes to roam, so at times we'll only have the one DM in position to win the ball back.
Just go with the 4-3-3, it's better.