Longtime readers of this column may note that I have always been a fan of silicone sealants; however, I worked for a manufacturer of these materials for many years, so I hope I can be totally objective. I have no doubt that the durability and longevity of silicones cannot be exceeded in most applications. However, I can offer you several observations from my personal experience using them at home.
Adhesives are often a better way to assemble plastics than by using mechanical assembly with fasteners. For example, fiberglass composites are routinely bonded with epoxy or reactive acrylic adhesives in the automotive and marine industries because they give high strength and durable bonds.