"Whenever I install refills I have visions of them slipping out while in use and the frames scoring big arcs across the windshield. It's just me I guess. "

No, not just you. Me too. Happened. Unfortunately the family member operating the vehicle was not aware the arm could be lifted off of the windshield (it was the passenger side). Drove 20 miles like that.

We have since replaced the windshield, but the root cause, I'm certain, was my fault in not getting the arm properly locked into the wiper blade. Not quite the same as a refill gone wrong, but same result.
--
Art Benstein near Baltimore

Evidence has been found that William Tell and his family were
avid bowlers. Unfortunately, all the Swiss league records were destroyed in a fire, ...and so we'll never know for whom the Tells bowled.