The main issue that hurts our team at the moment is the players conditioning and fitness levels imo, not whether we play the 443 or 352.
As some here already said formations are mostly just numbers, fit and well conditiond players can take any formation relative advantages and impose them on the other team as long as they are able to stay sharp and combative.
Conte's method of a killer off-season training was very fitting in he's first season here, when we only had the league to compete in, however Conte lack of exprience in playing on two fronts seems to cost us those last two seasons and in the CL even more so as the tempo is much higher even against the "lesser" teams.
Players being able to run for 90 minutes is one thing, but players making good decisions throughout those 90 minutes when they are tired is something else and thats where the difference between us and the top clubs is imo, the differance in player conditioning levels is much wider then the difference in tactics or even indevidual talent and the second half against RM was a perfect example.
Lets hope Conte learns from this for next season or even the winter break if we make it to the next stage.