Over the last week I have been riding my chopper bicycle, which has a Lepper Primus saddle. It had been a few years since I rode it in earnest, so I had to reacclimate to the saddle.
It moves up and down (a LOT) just like I remembered. It moves side-to-side more than I remembered. And it bottoms out more than I remembered too, even though I weigh less now than back when I used to ride it often. It creaked like crazy at first, so I dripped a little chain lube on all the metal-to-metal contact points and it quieted down somewhat.
Bottom line? Its a good saddle for a chopper. A bike like that rewards a smooth, sedentary riding style, and so does the saddle. It's probably a good choice for an e-bike, too, if the bars are well above saddle level and there is no plan for fierce pedaling.