I have both Cliffy protectors and Mantis protectors installed on all my games. The general rule of thumb that I have applied is that if it is a pristine scoop hole with no damage then I install a Mantis protector.

However, Cliffy makes protectors for some scoop holes that are not made by Mantis so in that case I have installed a Cliffy protector on a pristine scoop hole. Both protectors do an excellent job of protecting the playfield surfaces that they are designed to protect and both options are created by excellent product/service providers (Cliff Rinear creates Cliffy protectors and Kerry Stair creates Mantis protectors).

For my TFTC, I installed a Mantis protector in March of 2018 and have since played roughly 500 games with the Mantis protector installed. After playing about 50 games or so I made a slight adjustment to the Mantis protector by lifting it up on the right side of the scoop hole to provide better protection for the upper right side of the scoop hole.

Below are some photos that show my TFTC scoop hole after roughly 500 plays with the Mantis protector installed. As the OP (Sean) stated, the Mantis allows very slowly rolling balls to drop into the scoop hole without being deflected.

Gord

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It probably wouldn't hurt, but the main thing it to bend the Mantis protector slightly upwards on the right side of the scoop hole.

Gord