Looks like in my case there's another UI conflict.
As i posted before, nuking the WTF folder and doing an almost-virgin UI with only epanels worked fine...i could exit the game, re-enter with no errors and my panels intact.
I added my other add-ons and got the error again, same as above.
(BTW i also used text entry for my panels)
I deleted all my addons and added them 1 by 1 to narrow down which was causing it, and in the process realized almost all of them were out of date since i get them from wowinterface or wowui instead of this site. I've now added all of them and now eepanels is working again. Sorry i couldn't help track down what the conflict is.