Did you personally observe the inside of the engine? If so, did you take any pictures?
Not sure how a significant engine knock problem would materialize with damage on our turbo engines. But, I would think it would be similar to what I grew up with: On naturally aspirated engines, if you were running to much knock; it would almost always blow a hole through the top of the piston and/or burn the living crap out of the valves. I don't recall ever seeing the rings let go from an engine knock issue.
Never got to see it opened up. All I know is what they told me which is pieces of the piston were found inside the oil pan... Don't really know what caused it.
Mine - '08 Brazen GXP. Trifecta tune, Magnaflow exhaust, DDM backbone and brace, rear Z0K sway bar, Eiback springs, debadged, 19" wheels.
Hers - '08 Bluestone Redline. GMPP tune, Magnaflow exhaust, DDM backbone, debadged (mostly). FOR SALE