If the photo isn't the exact thing you're buying, then eBay will uphold your complaint, doesn't matter if it's about the firmware version or scratches on the bottom of the case.
Well you could always try... I still doubt Ebay would see it of significant difference. Especially if you don't mention why you would want it to be on a lower firmware, i.e. Gateway
And call me too trusting, but I highly doubt many people would go to the trouble of faking an image of the firmware.