Law rights and wrongs aside, I've always believed it's the way you present yourself anywhere that you ride, that can become an issue at whatever speed or power.
Yes, you are most likely going to feel the full force of the law if you are involved in an accident on a heavily modded bike. But so are you if you ride a non powered bike like an idiot.
In the three or more years of riding a powered bike, I've never knowingly come across another ebike on my travels. I've ridden thousands of miles and passed hundreds of cyclists.
I've seen one guy fly over his handlebars right in front of me with a combination of inexperience of front hydraulic brakes and not paying attention. He was lucky to be wearing a helmet and not end up in hospital.
A few skid, slide type dismounts too. The offenders usually shake themselves off and we have a giggle about it, but things could have been so much worse.
Always ride to the conditions, know your bike and pay attention
Many many incidences of groups of cyclists totally hogging the path going both ways. Even a polite ring on the bell seems to inconvenience them to move over slightly to let you pass. No rush, I'll just tag on behind until it's safe to pass.
Also, many incidences of cyclists flying round a blind corner with nary a clue to who or what's coming up. I'm always wary of blind corners and slow right down. Why take the risk!
And generally a lack of awareness of their surroundings, vehicles, pedestrians and bikes around them.
Yes, my bike can go a little faster than the average ebike, and yes, it can power up hills as though they weren't there, but what I do use is a lot of common sense, spacial awareness and courtesy.
I have never upset, inconvenienced or been involved in an accident with anyone!
Some will say luck and my time will come, but until then, I will continue to utilize these skills and watch others make fools of themselves.