Kern,
The GM HEI has less external connections/connectors that can become loose connections or corrode. So from that perspective alone, it is more reliable.
A measure of the ignition's ability to fire a big plug gap is testament to the design & for inductive ign systems, the HEI wins hands down & is better than the Chrys system for reasons stated in post #22. I have run 0.125" plug gaps with HEI ign. Made no difference that I could feel, but certainly no misfires to 5500 rpm. An engine that I tune for drag racing in a 4000 lb car [ without driver ] has run 11.65/118 mph with a 3.31 axle & TQ carb. It has the MSD HEI module, 0.070" plug gap with Iridium plugs & runs to 6500 rpm.
HEI dist are now made for engines that previously were never equipped with HEI, Fords, Holden Chrys etc. Note that NOBODY is making Chrys dists for GM, Ford, etc. There must be a reason for that.....
Manufacturers do not spend money upgrading ign systems unless they have to & when they do they are looking for a more powerful spark, not less.....
One manufacturer { I believe it was Honda } built an engine in the 1980s that had a separate mini combustion chamber that created a 'fire' to ignite the main chamber. They obviously thought bigger is better....