I don't use the rear wiper, and removal is a win in terms of both weight and aerodynamics. My scale shows 1.1kg or 2.4lbs without the wiper blade attached.
While working on it, I took the time to repair the "spoiler". Sun damage had removed the clear coat, and some of the mounting points had broken.
Rear wiper motor exposed by removing the trim:
Pic showing the sun damage to the spoiler, as well as the 32mm hole left by its removal.
Some JB weld applied to the plastic tabs on the underside:
32mm glass plug installed w/silicone, and spoiler clearcoated and wet sanded to a passable finish:
