My first choice will likely always be, glued and screwed. Why...because glue only fails at the worst possible time! Lol! Really, glue is fine for many years, most of the time. The only time it's not...is when it's not.
Curiously, when I was doing vibration testing for tuners, I had a glued and screwed gun that we tested both ways. We tested and measured frequencies, then I removed the screws and scope..and laid an iron on top. It came out nice and clean. I then screwed it right back in at the same torque setting....just a good bedding job at this point. It shot fine both ways but at different tuner settings and the frequencies measured at the muzzle were a bit different. It's a joint in the system..No matter what you do short of unitizing parts by welding or gluing, there is movement. The movement is at high frequencies, that I don't think hurt us or simply get lost in the noise. Nevertheless...all else equal, the muzzle vibrated at a different frequency as opposed to being glued and screwed. FWIW--Mike