You are absolutely right about the components! Bike frames, brakes, wheels and tires are not meant for sustained 40-50 mph speeds, in particular with the extra weight of large motors, batteries and other accessories. At 245 I am on the edge with a number of components when pushing hard.
I hadnt thought of the insurance.
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Having said all that, for s***s and giggles I did try an ST1 Stormer and was very impressed. Took a little while to get used to the extra weight, but this would make an ideal long-range commuter. I've tried pure pedal from CT to NYC and round trip is a little much. But with a little assist to "flatten the hills" it becomes a viable proposition - and not having to pay for a train ticket might be a nice.
/off topic