I agree that Syclar should retain both abilities. After looking through the Syclant material, it sounds like this CAP was given Mountaineer because people were paranoid it would be neutered by Stealth Rock or a good ole Stone Edge to the face. It might not be a bad idea to work the Mountaineer angle into Syclar's pokedex entries.
That being said, I vote for Mountaineer and Compoundeyes being retained as the y are the signature line. Also, most bug lines keep the same abilities (except for those worthless lines like Caterpie and Weedle).