I dont think there are any disadvantages or advantages just a personal preference if you solid mount the motor I do know the trans needs to be solid or it will break bellhousing on the trans vice versa if one is rubber the other needs to be rubber just some of my advice if it means anything to you.
yep mine had poly mounts on motor...tranny was hard mounted and transfer case was poly and it broke the tail housing on the tranny completly around....went back with poly on tranny and have not had any issues since then