coming from a gm tech standpoint, just so you know, if its serviced correctly, dex cool shouldnt hurt the gaskets and what not, but i do agree if you are having it power flushed, just go back to the green coolant. its cheaper as well.
but what kind of car did the head gaskets go out on at 80k? we do at least 2 head gaskets jobs a week right now, on 3100/3400 motors...first it was the lower intake leaking, now that they fixed that, it starts to leak at the rear head below the powersteer lines. very common, not before of dexcool, but because of poor design of the gaskets