Forgive my noobish question, but what would be the benefit of updating the firmware?
In general, if there's nothing wrong with your DMS - then you'll have no need to fix it. Generally firmware updates resolved particular issues with head unit support, and the odd bug in controlling the Phatbox. Unless your box is still new out of factory, or needs re-programming for use with a different head unit, you are not likely to need to update the firmware.
These days of course we have the DMS Tools which can do this for you too and is probably more lightweight, but this now gives people an alternative method of switching firmware.