Switching back to 3×9 because I’m a big jessie, I’ve been using cheap clarks for the rear, having to replace every now and then due to the local sandy conditions.

Is it worth spending the extra for Shimano?

I’ve always bought bulk outer (end caps & ferrules off ebay) and inners as I need them. Though I run a number of bikes, repair other ppls bikes, & run full outer on all my bikes, so it make more sense. That said, if you only have one bike, the shimano kit contains a comprehensive set of seals for the cables, which do work well.