What? ^
It really depends if your brother is willing to maintain a rotary. They are great motors, as long as they are kept up with. You need to make sure not to lean it out, and keep it cool, I've had many friends daily rotaries with no issues, it's all up to the maintenance.
Also, to address MPG, a naturally aspirated 12A really won't be getting that bad of gas mileage as opposed to a turbo'd 13B.