Joea-
If you couldn't tell from my response, I'm in favor of the Holley 750 with vac. secondaries. In fact, it just so happens, that a Holley 750 with vac. secondaries is exactly what is sitting on top of my shiny new 428 that is currently sitting in my garage anxioulsy awaiting the arrival of ERA 650 to call home.
BTW, I have the 4160.
All kidding aside, for the reasons I described above, I think a carb with vac. secondaries is better than the double pumper for street driving.
Mike