yearly or so reminder that PBW at recommended concentrations can eventually damage Better Bottles. Depending on your concentration it doesn't even take that long. (Buckets seem to be fine.) I get around this by inverting the BB after a little while so it can continue to work on that stubborn krauesen ring without sitting on the bottom of the BB and causing any caustic stress cracking.I do not buy it.
PBW is non caustic alkaline cleaner.
To my experience PBW work the best at lower temp range.
I speak from experience, but if you do not wish to believe it, by all means do not. I know what I will and will not do again with PBW and am comfortable with my current procedure.
a simple google search will turn up many people who have ended up with something that looks like what you see on page 8 here.