I've used both and I like and use the Tefgel.

Example, I installed a couple spinlocks low on a mast three years ago with #10 machine screws. It's used a lot in salt water only. Recently I removed the mast base to mess with something else and I had to remove the spinlocks. There was zero corrosion at the mounting holes. You could also see where the Tefgel had soaked into the aluminum about a 1/4" out from the holes.

When you put larger fittings on a mast put electrical tape on the back of the fitting first to help insulate it from the mast.