I've got dillema too (bigger one) so I'll just post here instead of creating another thread.

Basically, I lost 1-3 at home against pretty defensive opponent formation (something like 5-3-1-1) who has just slightly higher team-rating than me (both lvl 2). Since my 4-4-2 wide formation didn't bring me satisfying results this season I changed it. But for the second away leg, in which i have to win 3-0 or higher (or draw with 3-1 win) I intend to go full attacking formation, I had something like 3-5-2 in mind. Any tips?