Hey headkaze,
We both have the exact same setup on our cabs. I keep updating to the latest because I figure that 'one day' I will upgrade the PC in my cab if/when the new versions of MAME either make the roms so slow they are unplayable or the new versions of MAME start making the majority of once unplayable games playable on a 64 bit OS running duo processors. I know it already does to some extent.
At any rate, when I do upgrade to a better PC, I don't want the hassle of updating the romset from an older version of MAME to match the newer...so I always update my MAME at every version so the change in the romset is manageable. SO...when I do get a new PC, everything MAME related with be the latest.