I am a former ad valorem appraiser over twenty years ago. Do you belong to the IAAO? My first designation was the RES, got it just as I was entering fee appraisal--so it was never applicable while an ad valorem appraiser, although I hung onto it for about 15 years--just because it had taken so much work on my part. Number 97 by the way--so you can see how long ago that was. Does the IAAO have a chat room? I don't even have their webiste, but call their Chicago office.
I have in ad valorem appraiser since 1979 starting at the schoold district level and now work for a county central appraisal district in Texas. I quit tax appraisal in 91 and tried something new for a year but that was not what I wanted to do. I got my real estate license, got my General Appraisal designation and went on my own for 8 years. I came back to tax appraisal because i am a masochist. Actually, I do enjoy the work, which is the reason I have returned.
I am not a member of the IAAO but have been considering joining. I have a Registered Professional Appraiser designation, but like your designation, it is only good for tax appraisal work.