Would be a move that would help Juve stop Bayern playing. Extra presence in midfield and make it easier for Juve's midfielders to move into wide areas without leaving Juve light in the middle of the pitch, so it could solve the issue of Juve having a problem with being out-numbered on the flanks.
However, it would have to be considered a very negative move.
Bayern's weakness, as has been well publicised, is there CBs. I'm not sure I'd be up for not playing two forwards and trying to expose that weakness of Bayern's.
Moving to a 3-5-1-1 would involve trying to beat Bayern by taking them on where their strength lies, rather than really looking to exploit a weakness.
Playing Vucinic as a lone striker would also remove any possibility of Juve being able to playing long and early over the top to try and take advantage of Van Buyten's lack of pace or just having a striker running behind the defence with a view to stretching the game out with a view to opeining up space for Juve's midfield to be able to play. Vucinic would continually offer short, and could lead to the game being very congested and Bayern being confident enough to really push their defence high up the pitch. That would increase the chances of Juve being pinned back and under serious pressure for extended periods.
It's a fine system if all you are doing is looking to try and get out of Munich with a 0-0 or a 1-0 loss.
If you are looking to make a serious effort to get an away goal, I wouldn't play 3-5-1-1.