I had the old, round tray, Lee priming tool and liked it. It bottomed out for a perfectly seated primer with the lever completely closed and you had maximum leverage. I would still be using it, but I wore it out.
The new square tray is junk. Primers seat in the middle of the stroke, That makes it hard for someone with a weaker grip from a mild stroke (me) or arthritis. I have to use two hands to seat a primer.
Jams and flips primers all the time.
They must have had some primer detonations to have to redesign it with the shield next to the primer being seated.