I’ve seen some anecdotal evidence on it as well, but this is actually a method that has been studied, and the studies show either really small girth gains or none at all, and it is usually statistically insignificant.
As far as the anecdotal, it seems that I’ve heard many people who are frustrated with ADS because they don’t gain any length, but they keep gaining girth. Why this is, I don’t know. Maybe they are doing it wrong and somehow their set up is conducive to girth gains. Just a guess, though.
Either way, pretty much all ADS do the same thing, and it never hurts to gain length, so the question I’d be asking is what is the most comfortable, most discreet, and best bang for your buck? I’d like that question answered myself :)