I tend to dislike the "safety undercuts" but it does depend on the focuser/diagonal in use. In a TV Everbright with a set screw, they seem to work nicely.
One problem I haven't seen mentioned is that in a focuser/diagonal with that uses a non-captured screw, I find that I sometimes end up backing the screw out too far and dropping it. With a smooth sided eyepiece, it only takes a small twist and the eyepiece is can be removed, with the undercut eyepiece, it takes several turns and can result in the losing the screw.
jon
One problem I haven't seen mentioned is that in a focuser/diagonal with that uses a non-captured screw, I find that I sometimes end up backing the screw out too far and dropping it. With a smooth sided eyepiece, it only takes a small twist and the eyepiece is can be removed, with the undercut eyepiece, it takes several turns and can result in the losing the screw.
jon
