You are trying to tell me dat a BIG disadvantage of Big turbo's is actually a blessing in the sky? I am more fond of low down torque my self. And what's that going to mean for the mileage? Not great news I suspect, unless you're a shareholder of an oil company.
And if you drive normal with the flow of the traffic you don't need turbo boost. You never need it for cruising at speeds up to 115 mph. So with a speed limit of 70 in the UK most of the driving will be off boost, no matter how big the turbo is.

I have driven more than 200.000 miles with stage 1 chips (both 2wd and 4wd) and never had the urge for more. Besides, even in Germany a good stage 1 goes right up to the top of the tacho (7000 rpm) in 5th gear. That's enough for me.