I suspect that it would be easier (though I don't know how practical) to simply zero the exponent for arguments that are getting upvotes. At least then it doesn't penalize the discussions generally accepted as quality.
Or, slightly more moderate: suppose the delay is depth^1.75 seconds: each upvote could be a slight reduction in the 'depth' factor: (depth-score/3)^1.75 or something like that. Could also be useful because becoming more "flamey" means you're actually increasing the depth via down votes.
