When you say "without ducts" do you mean oem setup or simply just removing yours and not putting the oem contraption back on?yeah, at that level of shroud cutting you really may as well just take it off.
For what it's worth, i think the shroud does serve some purpose when it's hot, the car is not moving and the radiator fan is on. there's a bit of space between the fascia and radiator, intercooler, and other bits. To me, the shroud appears to direct outside air through the radiator rather than hotter air trapped there, coming from engine compartment. once you're moving, it should make no difference temp wise. I've been doing some logging on intake temps with the ducts and without, and once you hit 60+, not much difference.