doubling the batts doesnt double the amps, just the voltage.
and as you said, the 80amp rating has more to to with how much amperage the Motor will draw through the ESC.... not how much the batts give to the ESC.

a pair of 2s 30c 5000mah lipos will work great in the 8E's. No worries of it burning up. such batteries will provide more runtime than the stock lipos, but not cause the ESC or motor to work harder.