On some vehicles I've seen a wiper arm delete wouldn't even make a difference because it is already out of the air flow. Unfortunately on my CRX and Tacoma both have the wipers in the air flow but when it comes to rain, I have rain-x (amazing) on both vehicles and I keep both wipers on when it's raining. It makes me feel much safer and I'd never know if having that little bit of extra vision will be helpful or not until it's too late.
Now during the summer I will remove the passenger arm and I'm sure there's an aerodynamic gain from it. I'd rather have it and not need it
