Was going through Herms's Strength Checker, and Roshi does, indeed, assert "
Goku will never beat [Tien] with a Kamehameha!!" and "
The Kamehameha itself doesn't work against him, no matter how powerful it is…", which may imply Tien directly scales above the Moon-Destroying Kamehameha, either via sheer strength or via Tri-Beam; although, considering by the time Roshi made the comment, Tien had already exhausted his life energy using the Tri-Beam, I am inclined to believe the former condition. That, and Roshi
also describes Goku as possessing zero weaknesses, which may also imply he has transcended Roshi's own ability,
which Roshi
later posits himself.