Sounds interesting... If I had to buy again, I'd definitely get a dual battery. I can see several advantages:
- Both batteries are securely fastened and locked down. No need to carry around a second battery in your pannier or in a bag.
- The batteries are discharged alternatively in small percentage increments. This means that the discharge rate is slower for both batteries, which increases their lifespan.
- Both batteries are recharged at the same time. No need to have 2 chargers.
- Doubling the capacity means you'll have sufficient range for unexpected trips during the day.
- More battery capacity would make the bike easier to ride in spring time when it's windy (more use of Turbo mode).
- An S-Pedelec really needs more battery capacity if you live in a hilly and windy area.
I was extremely tempted to buy the dual battery R&M Charger GX but decided against it because it was too heavy (I need to carry the bike up a flight of stairs). If Haibike puts the dual battery system on the Trekking series, I'd probably sell my current e-bike and switch. I'm surprised it has taken e-bike manufacturers so much time to follow R&M's lead.