I have a mechanical unit and I love it
I have been tuning Chrysler type advance units for probably 30 years
So this units advance weight system is much like the Mopar unit.The nice feature is the ajustable plate you can tune with a phillips screw driver to set max advance.I was able to set mine with only 10* advance for easy starting for a street/strip car.With other distributors I could actually watch the advance move and be erratic when trying to set total timing but with the Firecore the timing is rock solid from idle to 7000 RPM
This is one of the parts on my car that is actually worth EVERY penny
Treat yourself to a set of Rick's Firecore wires as well for the total secondary ignition setup.
Gus