I'm on the fence for the 352.
On one hand, I know montella likes it and I'm sure he can make it work. It's also a very flexible formation. I'm actually surprised montella has waited til now to use it, excluding the few times we subbed on Gomez to close out games.
On the other side, playing a 3 in the back means we need two new wing backs, and two new centerbacks for the starting lineup alone. That's a lot of investment for a backline that statistically is the best of our three units. And while we have money now, this team will be needing a huge top to bottom overhaul. Also from a playing point of view, assuming we sign Keita or another winger plus a striker, either Suso or Jack gets pushed out of the lineup. I don't like that, I think they have carried the teams creative duties and they back that up with stats. Forget about Susos poor end to the year, he wracks up assists and is a big game player. He and Bonaventura I would think will do better next season when they won't be our only threats also.
The best, and maybe most likely tbh, solution is probably to use the 352 as a fallback. Not our main formation. For me at least. Montella knows best and I fully trust him. But I'd rather stay 433 and use 352 for specific games, instead of using 3 in the back predominantly