I just set it up myself, and the only thing I used it for was just tracking serpent sting. I turned off all of the other buff/debuff stuff. It seems to be working quite well for me so far. Here's what I did to setup the serpent sting bar for myself.
Under "Bar Groups," click "New Auto Group".
Select "Auto Debuffs" and "All Cast by Player".
Under "Filter List" , select "Whitelist" and add in "Serpent Sting".
That's all you have to do to get just a serpent sting group. I'll leave the visual settings for you guys to figure out as I'm lazy.
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There are probably a few buffs I've missed that gives stats (like Dalaran Brilliance as a replacement for Arcane Brilliance). I think I've found a couple of them since I last exported the string. What I used to get the buff names is the MMO-C raid comp, which does seem to be missing one or two. I'll be uploading a new version sometime soon with some of the suggestions from over Christmas.
As for the double countdowns, it almost sounds like you might have two versions of the aura group imported. Shoot me a screenshot of what you mean, because I'm not having any problem like that.
Is there anyway in Raven to make the bars grow down instead of up? Also, can you offset the label text on the X,Y coordinates because I could not find any of these options.