Experience with a Rohloff eBike
I thought I'd chip in with some real life experience. I converted a Thorn Raven with a Henzemann electric motor in 2004 and then rode it for about 5000 miles a year until 2010 when I sold it.
The Thorn Raven is a Rohloff specific frame, but with the high mileages I was doing, you still had to adjust the chain tension (at the bottom bracket) every 1000 miles - i.e. about every 3 months. With hindsight, I would always recommend a frame with vertical dropouts, a Rohloff with a torque arm and a Rohloff chain tensioner (the best on the market). Once you have fitted it all - no more maintenance for over a year. Just add oil.
My maintenance schedule was ludicrously low. Oil the chain when it squeaks. Fix a puncture in the Marathon Plus tyres once every two years and every 10,000 miles change the chain. After 30,000 miles I took the Rohloff cog off and turned it around to even the wear.
I spent 3 years moving the batteries over the bike - high on a rear pannier, low on the rear pannier, low on front panniers, on the top tube, etc.
My optimum solution was to attach a custom mount onto the seat tube bottle cage and the down tube bottle cage. Tie the battery on with a toe strap and off you go.
With the weight of the batteries central and low, the weight of the Heinzemann balanced by the weight of the Rohloff, drop handlebars and tri-bars, I ended up with the electric tri-brid. The Marathon Plus tyres were fitted to super-strong Atom Pimp Rims that I hand built with extra strong spokes and ran the tyres over-pressure because the rims could take it.
Result - A bike that you could time-trial on the flat without assist at 23mph, it would climb hills at 16mph despite the weight and would descend at 40mph because of the weight. Once you got it going, it handled like a regular race bike and the weight was invisible. I often fitted a second battery to get the range up to 80 miles.
My advice - GET THE ROHLOFF. It is a superb piece of kit and lets you enjoy the riding without the worry of maintenance. The Alfine by comparison is fragile and quirky and doesn't give you that even 10% gear change with every click.
Bruce