Fortunately for me, I did get my insurance to pay for a multi-level ADR in the Cervical using the mobi-C. It only took me 3 months to do three appeals but the key is responding back within a week of the denial. If you take the 30-45 days to do the appeal, it will take longer.
The problem I see is people don't want or can't fight and the insurance companies are banking on you giving up. In my appeal, I researched evidence based practices on the www to show that this procedure is not investigational. I also included medical journals that show that fusions are more costly then ADR and that studies show the recovery period is quicker as well. I included the studies as evidence.
I explained in my appeal the reason why I didn't want fusion and that I should have a decision on what is right for my body and how the artificial disc was going to be better for me due to my activities and active lifestyle. In my particular case, my injuries were inflicted when I was on active duty and I emphasized it in my appeal.
Don't give up. There is hope -- we need to fight and show insurance that were not going to take "NO" for an answer anymore.
Good luck!