i agree with general consensus, ratings will only skew the search results bypassing the contents of a thread. & as f0dder pointed out, the older threads will get left out..
on the other hand, it might be easier for user to locate threads with useful tips/solutions/reviews/workarounds etc. since it has already been verified by the responsible & impartial folks of DC.
maybe only members at certain levels can be allowed to vote but then it will sound as elitism..
anyway, as the cliche goes, it's a double-edged sword or something like that.
(i know, i suck at cliches). just my 2¢..