and you would probably need to run a bit more font wing to get the extra performance out of the f-duct/rear wing.
Otherwise you may just end up understeering through the fast corners.
This will add to the "drag penality" - IMHO
Anyway, there are different ways to skin a cat, we will see what the teams learn and decide after there back to back tests on Friday.
I would think no F-duct is a sensible approach to Monza.