I am not sure why if even matters to look at "evidence." Every type of treatment inflates its claims of success. No surprise there. And who cares anyway?
Statistics and proof do not help any of us as individuals find what will be effective for us. It is like anti-depressants--the statistics do nothing to tell any one or any doctor what will be effective in any specific case. You just have to to keep trying till you find the one that works.
Knowing that x number of people were helped by Prozac or SmartRecovery ultimately does not help us figure out what we need to do as individuals. Sure it is interesting intellectually, but it does not help in recovery to know that only x% of people recover through this or that program. Even if only 1% get helped by a particular program, then I want that 1% to find it.