If the Eternabond is installed correctly it is very good.
My experience with it has been when it was not installed correctly. It is a pain to fix a leak after a botched eternabond job.
I stick to Dicor, Sikaflex, Geocel, or Alpha.
A friend used eternabond around his skylight which was plastic with triangular gussets all around. He had to split the tape to go on each side of each of the gussets which was a bit of a pain, but has happy with the outcome.
Joe and Evelyn