Ported Vac or Manifold Vac

Just stirring the pot: I'm technically running manifold vacuum to my spark control, but I'm faking a ported vacuum advance curve electronically.

Although on a more serious note, an advance curve is an advance curve, an air/fuel ratio is an air/fuel ratio, and the engine doesn't care how you set them. Too much advance gives an unstable idle whether it's from a computer or an advance can. Some full on race cams may benefit from 24 degrees of idle timing, but it's rare for this to be ideal on a milder engine.