If an engine makes 400 hp and 390 lbs of torque it doesn't matter to me if that's at 2 psi, 10 psi, or 75 psi. Power is power. And if you have to depend on more boost to make it, you're probably going to have more lag.
And the gas mileage on powerful V8's won't be too bad if you don't floor them all the time. The Z06 Vette has 405 hp and gets 28 mpg on the highway, 19 in the city. The supercharged Lightning gets about 16 mph highway and that truck has a lot of drag and weighs 5000 lbs.