Originally Posted by
pbass
Having never tried one, I have pondered this very thing: don't they weigh a ton? I guess you could use that as a workout component!

Yeah, they definitely weigh more, though I expect that will be a continuing area of improvement.
On the road, I'd think you could get a very good workout. There are several YouTube videos that clearly show you can still put in a good amount of work on an e-bike. For people who normally ride on a MUP, I can see that you may not really be able to go much faster (or shouldn't) as a safety issue. But on the road, especially hilly areas, I think they'd be a blast.