Physical differencies between the 708 and the 716 are that the 708 was the last drive with a headphone connector in the front panel and the 708 was still the “long” build-style of 19cm while the 716 was the first drive with short stype (about 17cm).
Other than that i think the firmware version is an indication that this drive comes out of a copy/duplication tower (we had an earlier thread on this). 1.69 probably corresponds to 1.09 in regular firmware, so you can update to the recent 1.11.
And no, i don’t think you can crossflash a 716 to a 708. This is probably just PTPXL getting messed up.