[olddog]

At WOT it does not matter. At cruise it does matter. How much time will you spend cruising? How much time will you spend with it mashed to the floor?

Let's look at it another way. Suppose you had a perfectly tuned engine that obviously has vacuum advance (it is perfectly tuned so it has to have vacuum advance). What would you say if I asked you to retard the base timing 20 deg, and drive it on a cruise? If you did that, how much power would you expect to loose at WOT?

Now understand that when you retard the timing you loose power. So at a cruise you have to burn more fuel by opening the throttle more. Or you could back off on the throttle, turn the timing up where it belongs, and make the same power, while burning less fuel.

It's just my opinion, but it is foolish to not run Vacuum advance on a street driven car. Now if you have an engine that is so radical it shouldn't be on the street, or if you have a race only situation, then it is foolish to waste your time tuning vacuum advance.

That is just my opinion, and I think you asked for it.