I did entertain switching to a flat hatch years ago but... I am all better now!
The hatch is indeed more aerodynamic than the flat hatch.I don't mind the hatch as it gives the car a slipperier look.
As an owner of both hatch styles, I appreciate them both equally.
In my opinion if the car has the bubble back leave it a bubble back. They do grow on you and before you know it you'll be all better to.