I sorta do the same thing for my different class combos and different toons... but I just make a copy of the Files in the Runes of Magic folder(it is a "hidden" folder**) that is in your documents section... and put those files in their own folder + rename it for the combo [Instead of having two copies of 1 or multiple addon folder(s)]
Set up UI and Addons how I want them.. do a return to char selection and exit game so it is saved...
Copy the files in the rom folder(again the one in your documents)and put those files/folders into a folder + rename it ie. druid/wdn settings or Wdn/war DPS Settings or Wdn/war TANK Settings
just have to relog when you change a combo and swap out the folders and your UI and Addons are exactly how you left them for that particular class combo

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I do not have issues doing this... and it's always a backup in case your UI and/or add-on settings resets
**the Runes of Magic folder in your documents is where all of your character Interface and add-on SETTINGS are saved