I chose roo bar, took it off, put it on again, took it off... now its on again
But then I live in Perth village, not the SW, so that would have me thinking about those roos around dusk...
I had a roo bar on the defender 110 and never hit anything in 10 years, never had anything attached to it (rods, aerials, winch)... It was 50kg of un-aerodynamic snow plough/ ballast... an expensive way to locate a license plate. I struggled to see the point, but then you don't need it until you need it.
Front end of the IG looks robust (and un-aerodynamic) without the roo bar, making decision less clear. But the factory roo bar design is well integrated... and i'd allow it to be an aesthetic as much as practical decision.