Sorry, I don't have any stories on transitions, and you are quite right, I started my dog on raw at 4 months old. However, I have in the past read on different websites that dogs have avoided all sorts of surgery and reversed dis-ease by going raw.
Some dogs may go through a period of detox for a month or two - just like when a human converts from a junk diet to a very healthy one. It's natural and needs to be understood so people don't worry that BARF is hurting the dog .. but that old toxic waste is being expelled by this.
However, I think even an older dog will keep what he still has and can repair some damage if he starts adding bones, because the much needed calcium in the bones will strengthen his current bones and teeth. And the crunching of bones will help clean the teeth too.
Raw meaty bones like chicken wings are excellent for digestion - because it's the natural food .. therefore easy to digest. Dogs have much more acidic needs than humans. There is a thread on a different forum that might be of interest to you: //www.curezone.org/forums/fm.asp?i=728409#i
(I am not proclaiming to be an expert, just sharing what I have researched myself)