Most high performance engines loose substantial vacuum on acceleration. This is why you often see an aftermarket vacuum canister. A mechanical advance is adjustable, and will always advance. No lag time. I'm sure for a "production" engine a vacuum advance is the least complex and reliable. (No springs to pop off, etc.) I would take a gander that the main reason we see vacuum advances on older production cars was primarily a cost factor. Just a guess.
I agree with the above. Mechanical is the way to go. My MSD ignition is great! The MSD pumps out a heafty spark as well. My engine starts almost instantly.
