I have Trijicon ghost rings on my 870. The Trijicons are the same product as the Wilson Combat version. I too was a bit leary about gluing the front sight in place but I did some research and found that these sights are on thousands of shotguns without problems.
Still, I did a couple things to make me feel more comfortable with the front sight. These things were recommended by Hans Vang and by the folks at Wilson Combat. First, instead of using the epoxy that comes with the sights, I used J-B Weld. Second, I had a friend pin the new sight through the base of the original bead. I can assure you that the sight is not coming off.
Regarding the sights themselves... they are wonderful. I used to think that shotguns just needed bead sights because they weren't made to be accurate. That is simply not true. Ghost ring sights allow for faster target acquisition and accurate shooting (with slugs) at distances out to about 100 yards. Bead sights just don't allow for that.
Good luck.