There are two types of miter key sled - one rides in the miter slots, the other against the fence. Which do you prefer and why?

It would seem that the fence riders are easier to make, but would need to get replaced more often as they get chewed up.

The slot riders would last indefinitely, but would be less convenient for narrow items such as picture frames or box lids. and would require some system for maintaining consistent position as the box is rotated.

Thanks,

Dan