I'd visit the older forums
PhalloBoards 2.0 and
PhalloBoards 1.0 and you'll see progress reports dating back to 2011ish. Although many of them haven't been updated in years, I'm still in touch with a few of the forum veterans and their health seems to be just fine and their results equally stable.
I had my procedure done in the Summer of 2011, with a few subsequent rounds in the years after, and I'm holding up just fine.
By no means am I one of the original people. But I had PPMA procedures in 2015. For the most part everything is still holding up fine.
I think I have lost "some" Girth over the years, but it would be less than a quarter Inch.