Has anyone out there had any expearience with marine sealants like 3M 5200 or similar?

On the back of the tube it says it is a permanent polyurathane glue that dries rock hard but apparently does not foam up like gorilla glue, you can lay down a bead and it stays that way.

My quandry is this; my boat is almost finished, I`m almost out of epoxy, and I have yet to glue in the hatch lips and bulkheads.
Is there any reason not to use some kind of glue in these areas instead of the much more expensive epoxy?