Simply put, that sales guy is either lying, misinformed, or both. Gritti is one of the lowest quality Zegna lines - a "value priced Zegna" line to attract outlet shoppers, quality similar or below ZZegna that is made specifically for outlets.
They may move production to a difference facility, but this does not indicate quality simply because it is now being produced in Italy. It is easier for smooth talking reps to imply quality when they suggest the facility has moved from China to Italy for the reason of improving quality.
Avoid Gritti.
XXX > Mainline ≥ Soft > Zegna Sport > ZZegna, Gritti, ItailianSuitsByNight