Worthwhile project email@example.com. I'll double your point about rounded ends. Radiused ends are beneficial, especially on blind slots, making use of all length possible, inserting easier too. Also less prone to jam in contours manufacturer milled in slot.
Admitting freely, small rotary tables need these just as larger do, inescapable. What ever table is at hand, some project is too big for the one available, and not only part wise...sub-plates too!
I prefer Tee Nuts be tapped through to broaden selection of stud & capscrew length. Often I find a setup needs as low-profile clamping possible. But on the fence about suggesting them without caveat that running fasteners all the way through exerts force in the wrong direction; breaking out Tee slots or marring inside where Tee Nuts won't slide along anymore. 2 trays, fasteners in appropriate lengths won't set you back as much $.$$ as replacing tooling or fixtures.