Yes. I had it rebuilt twice. What a bummer that was! But it wasn't for this problem at all. The main symptom I experienced before each rebuild was that it went into "limp mode," with the light on the dashboard that would come on, and I'd have to pull over and let it reset itself. When the transmission people inspected the ATF, it was a horrible grey color with teeny bits of metal floating in it. Both times, they had to replace several clutch packs. Again, it didn't shift well and would go into limp mode. The metal parts were all grinding against each other, leaving the bits and pieces in the oil and making it black.
This problem, on the other hand, does not cause the limp mode light to come on, for me. I have very clean ATF, and the car shifts through gears just fine. That being said, I am pretty certain that whatever is causing it will involve opening up the transmission. They'll need to open it, fix the problem, and then seal it up again. But I don't believe it will require a rebuild of the whole transmission. I just don't know what the cost will be to do whatever fix needs to be done.
It's interesting that the shop thought it was over-filled. The shop I went to initially thought that, too. My regular mechanic did mention the torque converter. He made some notes on the bill during my last visit of what he thought it *might* be. I just need to find them. (I've moved recently and can't seem to find anything!) As soon as I do, I'll post them here. I may even just call him and ask him to call the transmission shop, since they know each other. I just thought I'd do some research so that I'd know what I was getting myself into.
Just make sure you don't drive with low ATF. If you're spewing it out often and it's not being replaced, you could end up with bigger problems!