ported vacuum is zero @ idle.
manifold vacuum or ported vacuum are identical off/above idle.
with no load having xx* of vacuum advance is not a big deal especially idle or lower rpm.
under heavy load having xx* of vacuum advance can be a big deal aka detonation.
I suggest you plug in a vacuum gauge and watch it.
It is very easy to hit lower vacuum even at part throttle.
You will not have 16* vacuum advance for long using the skinny pedal, even lightly.
Any decrease in vacuum = decrease in vacuum advance.
having vacuum advance in place @ idle tends to give a snappier throttle response vs. having it on ported where cracking the throttle results in a big change in timing.
folks have been arguing about this stuff for decades.
'88 GW (aka Babywag) and '90 GW (aka JUNKbucket) both fuel injected
1994 Caprice wagon