Holley double pumper vs vac secondary?

Hi All,
When I bought my 71 Dodge Demon 340 it had a holley double pumper on it. Was pretty bad on fuel but when you nailed it you were instantly gone, loved it. But like I mentioned was bad on fuel. So I replaced it with a brand new Holley 680 street avenger. Was obviously better on fuel but you always get that slight delay every time you gave it some.
My question is, if you drove the car exactly the same to compare both carbys what would be the % increase with the double pumper over the vac secondary.
My reason I ask this is I'm thinking of putting the double pumper back on. I liked it that much. I put 98 octane fuel in it here in Aust. (which is the highest you can get at your local bowser). The car is only a sunny sunday driver which probably only does approx. 5,000 miles a year.
Cheers,
Glenn.