Yes, I've towed all kinds of trailers. The rounded shape doesn't make a bit of difference. The only thing that does is if it's lower than the tow vehicle, then it's much easier to tow.Have you compared this to a square-shaped trailer? How do you know it's not any more efficient?
You've also got a pretty large flat area in the back that still creates good amount of drag. A true tear drop trailer @85_Ranger4x4 was referring to would significantly reduce drag and improve aerodynamics.
a 9' trailer is a 9' trailer no matter how it's shaped, you're going to feel that wind. It's like pulling a billboard down the highway no matter what it's shaped like.