I was looking at the throttle on a bike in 50cycles this month. I was quite jealous. It was a big soft rubber grip of typical ergonomic shape. All their controls were well finished. Their prices are also outstanding, which is why I didn't bother trying one. It would be a good way to benchmark a mid drive bike though.
I have a bpm as my daily. At legal power levels it fails to get up quite a few hills, and any sort of embankment is a no no. It's better than smaller motored 250w bikes I have been side by side with, but it's not a big enough upgrade to make any real difference. I have run at 15 amps (44v) but it still won't do most hills satisfactorily. This is in a county almost flat compared to derby. Home of the peak district.
How much more power do you need nanny? Perhaps your bike can be tweeked, or the bpm might suit you. I feel the best legal climber will something mid-drive though, It's just physics.