The biggest objection people have about Nani is that he will not fit into the 352 so they worry he sits on the bench.
However, the question you have to ask yourself is, is he world class? I think most people would say yes - and do we have a player with his characteristics? No. Therefore sign him depending on wage terms of course.
Conte picks the formation based on the quality of players he has - not the other way around. If Nani is in good form and can tear full backs apart, don't worry, Conte will use him and adapt the formation.
- - - Updated - - -
Besides, when they asked conte about the 433, he said: "we don't have the players like Ribery or Robben to play such a formation". That sais it all right there. Conte picks the players then the formation.
I am not "desperate" for the 433 and I think the 352 works rather well. However, unless you have the best players man for man in Europe, you need to have some tactical prowess to adjust play according to the opposition. When teams are successful in pressing our back 3, they cause a lot of problems. Having an "alternative" solution is important. Barca, Bayern and Real Madrid don't really need to adapt much because they can simply impose themselves on any opposition. We don't have that luxury despite having a very good squad.