Vacuum advance benefits?

I don't run ANY vacuum advance on any of my AMC's and they run great.

Beg to differ, but respect the opinions of others.

Holley carbs, both 2-Corner and 4-Corner, have Secondary Idle Circuits and delivery.
2-Corner carbs have Secondary Idle Air Bleeds, Idle Feed Restrictions, and Discharge ports.
2-Corners have small Constant Idle Feed ports located just below the Transfer Slots.
Transfer Slot fuel for both Primay and Secondary is delivered from the Idle Circuit.
Drilling holes in butterflies is less than a good idea imho and should be avoided.

It is possible to achieve full combined Intial + Mechanical + Vacuum Advance.
if Vacuum is high enough, RPM's high enough, and the Initial is locked in.
Dialing in more Initial without also limiting Mechanical can result in too much.

Vac Adv changes Distibutor Phasing when actuated, Initial and Mechanical do not.
Initial Timing moves the housing and Point Plate "Switch" relative to the crank.  
Mechanical Advance moves the Rotor Button "Trigger" relative to the crank.
Vac Adv moves the Point Plate "Switch" relative to the Housing and changes Phasing,
that is it changes Rotor Button to Distributor Cap Post alignment at the time of firing.
Mechanical and Initial Advance do not affect or change Distributor Phasing.

Adjustable Vac Adv Cans fail to allow adjustment of the Full Advance vacuum level
except indirectly by mechanicaly limiting the amount of total Vacuum Advance
by means of a Limiter Sleeve or an Adjustable Travel Limiter Stop.
A Point Plate alone is unable to limit advance other than the wire lengths
from the pick-up and ground, and the Vacuum Advance Can rod.

The tech article from the GM Engineer has been hashed out here so many times it is boring.  So much of it has been proven wrong over the years and some of the theories are based on wrong assumptions.

The argument about ported vacuum and manifold vacuum is decades old and most OEM’s went with ported and Chevy went with manifold. The antique cars that used vacuum advance first went with ported vacuum.

I for one will stay with ported vacuum on all of my old cars for both street and strip. Why, because it works. It doesn’t bother me if someone has their car set up with manifold vacuum.  I like the fact that my car runs the way it does when I get on it and how good the throttle response is when I get on it hard. Not everybody has the talent to set-up their ignition and fuel system correctly to get the peck performance that their engines are capable of.

I would say try it both ways and see which works best for you. I am tired of the arguments.

Happy Thanksgiving everyone, it’s time to go eat some Turkey and drink some spirits.