Electric vs Mechanical Tachometers

[ZLP955]

Interested in the pros and cons of mechanical and electric aftermarket tachometers.
For example, Which type is more accurate? Is there a delay/lag in displaying engine speed with one or the other? Possible interference with throttle linkage etc with cable drive type? What choice of tach drive distributors for an SBC (GM Corvette, Accel and Mallory spring to mind)?

[Kelley W King]

While most of my mechanical tach experience is corvette, I believe that they are generally more accurate but do have some needle bounce. Seems like when RPM is dropping quickly the needle will bounce more.