Looking for opinions about "aeroseal" on a house built in 1924.

The hvac was redone in 2018, but only some of ductwork was redone.
Has anyone had any success with the aeroseal product that supposedely seals all the holes in the duct work and makes it 40% more effecient?
Would you do new ductwork, new insulation, or try aeroseal if you were me and trying to reduce your ac bill? All seem to be similar price. Thanks!