Not that I know of (though I don't follow PitBull development anymore), but Shadowed Unit Frames has a smooth-bar-movement plugin, and has a very easy to use, but reasonably powerful, in-game configuration.
The agUF bar fader plugin was around for months and never got a smooth fading option. The PitBull bar fader plugin appeared to a port of the agUF plugin, so I assumed it was just there to do the same single thing and wouldn't be getting new features either. Not really much point in trying something again that I have no reason to expect is going to change.
Let's say my health is at 100%, and something hits me for 25% of my health. The existing BarFader plugin fades out the entire 25% chunk of my health bar in one piece. I don't want that. I do want the bar to smoothly slide from 100% to 75%.
I've seen Nurfed Unit Frames do this, and there's an old addon on WoWI from Gello that caused standard status bars to do this, but it doesn't work in 2.0, and obviously neither of these would help me get PitBull to do this anyway.
I've posted about this previously in an old agUF topic, but have since switched to using PitBull, and am wondering if it would be possible to create a smooth bar fading plugin. I was wandering around on the SVN earlier, and found this:
and thought it might serve as a good base for someone more knowledgeable to convert to a PitBull plugin.
Any takers? :P
Edit: The existing PitBull_BarFader plugin DOES NOT do what I want, in case you don't read more than this post before replying! To clarify: I DO NOT want the entire "lost" chunk of my bar to fade out at once. I DO want the bar to smoothly drop from the previous value to the new value.