Hi Luke (assuming per byline),
Welcome to the forums. That is a nicely researched piece, and the first mention of the Socovel electric bike I've seen. VisforVoltage posted a
contemporary review of the Socovel from a 1936 copy of
"The Motor Cycle" magazine, very interesting read. The introduction, drawbacks and conclusion section read like a contemporary electric bike review!
The Socovel electric bike had a maximum speed of 20 mph and 27.5 miles of real-world range at 16-20 mph. Additionally, the electric bike was much heavier, longer and wider than its gas counterparts .. the opposite of a modern Zero motorcycle. Amusingly, while under the same conditions I would expect to see 150+ mile range from a ZF11.4 bike, under 40-70 mph riding conditions the Zero lasts for 1-2 hours (70-100 miles) .. or about the same time riding as the Socovel.
I'll second Richard230 in that hybrid bikes are difficult case. Light motorcycles and scooters already get excellent fuel economy in the city due to light weight. Going with Piaggio's claims of 140 mpg vs 70 mpg with their hybrid MP3 would save ~7 gallons per month ($20) when riding 1000 miles/month. Beyond the packaging difficulties, hybrid bikes (big gas little electric) in city operation are up against electric motorcycles and scooters at their very strongest. A Zero XU offers 74 miles of city riding range, or typically 2-4 hours of operation. Quick-charging the batteries or swappable batteries can extend this out to all-day city operation if needed.
IMO pure electrics with a modular gas range extender make more sense (little gas big electric). A 10-12 kW gas genset would be sufficient for 70 mph freeway travel .. and could perhaps be packaged into a large tailbox.