I always just use Gflex Thickened Epoxy, and have never had a mount failure. I like Gflex because its super simple. When you install them, take your bolt, and coat it with something like candle wax, and thread it almost to the bottom. This will keep your threaded hole from being filled with epoxy and the wax will keep the epoxy from bonding to the bolt. One very, very important thing to consider when using these mounts, or really any aftermarket/homemade mount, is using the correct length bolt. If its too long, itll start penetrating the hull, and could cause the mount to rip off.