wouldn't it be better to abstain on the entire discussion rather than an individual reply?
That might be useful as an additional option but I think that some nodes can be judged even by someone with less experience in the subject matter. For instance, if I see a node that clues me in on the fundamental issue at hand, I'd like to be able to upvote it. Then, if I see another node in the same discussion which addresses a specific point about implementation, I might want to abstain to see if the node has a good reputation.
"My two cents aren't worth a dime.";