I have never used the loctite before. I have used the Marine Tex. It works very well. I have built 2 live wells out of aluminum and used the MT to seal the joints. One of the live wells is over 10 years old and is still water tight. Its very strong and holds up well and can be used in many types of applications.
But it is very expensive.
Maybe consider the "green stick" epoxy from attwood. You can get it at wally world ($15) in their boating section. This is great stuff, I've been using it to fill screw holes, bolt holes, gouges, etc.. Really strong, easy to mix and you can evan use it underwater in an emergency. I have decided to add it to my toolbox