We talked about this a couple of years ago morning star....it was well known that GaA's are brittle and difficult to manufacture in larger quantities without yield suffering....if I remember correctly we were also discussing the toxicity of GaA's at the same time.
I know we came to the conclusion that the yield/brittleness problem had been reasonably solved, I believe by something Dr.T had developed (should've kept notes on all this stuff, but I never expected to be here this long).....I think it was the method he developed to cut the wafers that solved the issue.
The toxicity issue was deemed irrelevant in the quantities we are dealing with.
Not sure how this relates to PET other than the yield question...in my mind, PET is dead, until it isn't anymore.
HTH