I believe the first MVVS gassers had a coil pickup sensor, not Hall. Later models all have hall sensors.
I like the lower / upper boot setup better. It completely encages the spark plug and uses a standard RDJ7J plug (topped off). Sometimes the lower boot tended to leak ever so slightly, but overall, the setup was very neat, especially the later models. These have the same setup as ZDZ.
The newest engines have discarded the lower boot system, and use CM6 plugs with a push on cap and either 2S (L- and S-versions) or 3S (P-version) LiPo cells for power.