-
That was my thinking but a 30mph collision with a pedestrian left me in hospital with a deep cut next to my knee that needed emergency surgery, a slice deep into a steel toe cap, crushed heel and twisted ankle despite having work safety boots on and that was on a scooter.
I can totally understand where you're coming from but sadly experience tells me it's got little to do with the weight of the engine.
I've never bothered with boots and trouser armour on the Vespa as there's no heavy engine to crush your legs.