Holley question, what do think of Vacuum Secondary vs "Double Pumper"?

Pinning a carb is taking it apart, and using number drills (at least that is what I use) to determine the opening sizes of internal passages and air bleeds. Newer high end carbs have some,or all, openings adjustable now, via brass screw-in plugs. Older carbs need drilling and tapping for plugs to be able to change them.
Edit: number drills come from #80 to #1 usually. 80 is tiny (if memory serves, .015) and #1 is .228. Use the shank and a caliper to measure, drill end to change sizes.