I believe these are Euro-only models. Looks akin to the Aprilia Mana. I'm digging the gas-tank-is-actually-a-trunk concept.
For a strictly commuter and short run bike, the convenience of storage is a very nice thing; especially if you are in the city. That said, I would generally opt for more fuel
Agreed, that looks like a great daily ride, digging the baby GSA. Wonder what the fuel cap actually is, and mileage, that little engine has to be relatively miserly. Edit- 3.7gal Specification Comparison - Honda Powersports @ 70MPG that would get about 250mi, ~200mi real range. That's a bit short for a bike that looks comfortable for really long rides, I'm sure the aftermarket will address this.
I'm sure a bladder system or blow molded tank could be added to the storage compartment with tubing to a quick disconnect in the fuel line to the pump (I'm assuming it has one) to extend range for the touring types. Should be fairly easy to make and would provide the option of removing the extra fuel cell when the storage was wanted.