Rich,
First, I have to tell you, the production Bibs have only been out a little over a year. So, if you mean gains from a production Bib, I doubt you would see anyone gain as much as I did, so far. However, there are a few guys who have gained at a faster rate than I did. lil, boxcar, Soma, and Merlin come to mind. Of course, most guys stop well before they attain the length that I did. If you go to PEforums, you can probably find a lot more reports of gains than here. Although there are quite a few here.
If you mean hanging in general, I probably am close to the top in gainers, if not the top. However, I have seen reports of many 3+ inch gains over the years, and quite a few 2+inch gains. The odds of the average guy gaining as much as I did are very small. Not only did I have the opportunity to work for many hours per day, I believe I was genetically and physiologically predisposed to be able to gain easily. You should discount my results completely.
On the negative side, I have had five reports of guys who either have not gained, or had extremely small gains. While that is less than one percent, I am sure there are more who have not gained and simply not reported anything. Probably at least 3-4 percent do not gain, even with a consistant effort. I have had four hangers returned, one unopened that a lady ordered. (?).
Before you spend the money on a Bib, it would probably be wise to try a homemade hanger first. See if you like hanging, and if it fits your lifestyle. Also, over a month or two, you can get an idea if it will produce gains for you.
Good luck,
Bigger