It's occurred to me the the firmware versions given in the list of approved devices is the usually the modem firmware, not the device firmware as a whole, which may account for the differences in version schemes. It also occurred to me that a device doesn't necessarily need to be re-tested if the modem part of the whole device firmware is unchanged, so the TalkTalk firmware might not need to be tested separately, if they don't change the modem firmware and driver.