I think that is an issue with the bosch system, you can only use the Bosch battery, and it can't be re-celled - the BMS will detect the change and it won't work. Also two batteries would presumably take twice as long to recharge as one, which might be an issue if touring, although I would have thought one battery would give you a decent enough range? At the end of the day, this looks like a top-spec bike, but the cost of ownership is correspondingly high.Also - bear in mind that batteries can be recelled cheaper than for a replacement - I had mine done recently and it was far cheaper even including an increase in capacity and using better cells. However, that isn't a Bosch battery - other people may have better info about that make.
I have had my super charger gx-rohloff about 3 months and all I can say its a great bike and to me its worth every penny got from York atany good for touring? Or over priced? I was informed the batteries would probably need replacing after 4 years. This would be about £1600 on current costs. Seems a lot to me.