Over the years I have heard all about various compounds to include silicon and 5200/4200 and others. As a former dealer, I will speak in layman's terms.
The silicon used to hold windows in is made by Dow but in essence it is an architechual grade 100% pure silicon which is strong and adheres very well which is why it is good for holding windows in place. I use to buy mine from a local Ace Hardware and worked well for many years. One main key is prepping the surface before application and that is where there will be a failure if not done correctly.
In the event of shroud chain plates, you have to clean all the old stuff out back to glass and if the gap is too wide between the chain plate and edge of the hole, like Centerline pointed out, you have to stop that movement and one way is what he did to stop that movement. I have used small plastic wedges too. Then fill in the hole with either 4200 or a good silicon. 4200 is not permanent. However, I used West Marine brand silicon actually made by Silaflex (spelling may be off) which is tenacious on holding, elastic, will not shrink and is resistant to sunlight. The key is overcaulking with silicon to let it ooze out when placing that cover plate back in place and let dry before attaching any shrouds. I have used that silicon in other repairs above water line.
As for 5200, you might as well call it an adhesive as it is permanent and that is used by boat dealers when securing keels to the hulls, secures the hull to deck joints. Again the key to a permanent and good seal is the prep work and above all let it dry for seven days before moving anything. Too many forget it takes time. There are ways to get it apart and yes there is an agent that will dissolve it but difficult to apply in some areas. It has it uses if applied in the proper applications.
You can clean up with either acetone or alcohol depending on the surfaces. If around any plastics to include lexan and so on, acetone will interreact and cause damage, so no acetone basically around plastics.
Again, prep work and the use of materials in the proper applications is the key as to what products to work with. Sorry Stu but 5200 has it place too and only if you knew what I know where else it has been used too. By the way, would you like to bath in 5200? I could not resist on that as it gave me a chuckle.