Considering that a bandwidth limit "factory option" can be something as simple as inserting couple capacitors (with specific values, that is), and most small SMD ceramic caps have no markings whatsoever, it might be impossible to see the differences visually. One might need to actually measure component differences between models.
That quite horrible looking soldering result in one the photos could indicate manually soldered components, which could in turn indicate that the BW limit would indeed be set at factory by adding the needed components to "stock" PCBs. Or it could just be a quick fix on a less than perfect board from the automated line.
But then again, if it would be so simple as 2-3 components, finding the differences would still allow relatively easy hack of changing those components by oneself. Even reverse-engineering the front-end might do the trick, but analyzing the differences might be easier/faster.