I'm guessing it has more to due with reliability and gas mileage.
While fuel pumps may be rated for 100% duty cycle, cars are not operated that way. Heat is bad for most electronics, so reducing the pump heat is probably going to a have positive effect on the lifespan. Especially, if the vast majority of the time will be spent at the 1/3rd DC.
Its could be the difference between having a fuel pump die at 100k miles and 150k miles. In both cases, the fuel pump has lived well into its designed life-span, but the second is better for overall reliability, which is what is tracked by Consumer Reports and other popular reliability sites.
Since you're already talking about modding the fuel system to perform well beyond its original design, I'd say it doesn't really matter either way.
To put the heat issue in comparison:
240W ~ 1/3 HP, assuming 30% efficent electrical system ~ 1 HP required to run the fuel pump. At idle, you're probably making somewhere between 15-30 HP, so about 5% of the engine power is keeping the fuel pump running at full speed. And probably a 0.5% change in EPA fuel economy. Its small, but if you do 10 small things you get a noticeable bump in mileage.