You'll see under apocrypha that the Nebula's cross section showed up in issue 154 of Star-Trek: Communicator, the main publication of the Official Star-trek Fan Club. In issue 154, the cross section shows that saucer separation is possible. I don't think Canon would disagree with this either. The Yoyodyne engineers who designed the ship completed it's construction only a few years before the galaxy class was completed, so it's very possible that their designs had many similarities.
There is also the question of the super structure above the main hull. Apparently, this could be fitted with several modules, both tactical and scientific. Meaning, sensors and torpedo launchers could be installed on it.
In light of these new considerations, I'd like for Cryptic to consider making a more tactical version of the Nebula refit with 1 or two additional torpedo bays added to the triangular superstructure. After all, the nebula class, aside from it's use in scientific missions, was used in patrol and transport missions. I'd also like for Cryptic to make the Nebula refit capable of saucer separation.