I don't know which loaches your planning (clowns?) but they will nip a larger snail to death We tried a mystery snail in one of our loach tanks, and he met a horrible end.
i also tried that some time ago with some very large snails in a tank with clowns, yoyos, and skunk loaches, and they were pecked at nonstop. fortunately i got my snails out in time!