Each variation of the Digg Spy has it's advantages. The feed-pulling one obviously is nice and simple and will work across a broad range of feeds with no work necessary, plus the reasonable amount of future-proofing against upgrades. On the other hand, the database one can easily be taken above and beyond a feed's fairly limited capbilities to pull more information from your forum should you want it to.
Win win, just pick the one that suits you best.