Based upon ownership of my first Endura (G-2, bought in '93), and purchase of another plastic clip Endura (also G-2) and a Delica (AUS-8), compared with my newer Delicas (metal clipped, ATS-55) and a Goddard L.W. (ATS-55):
The plastic clipped versions seem to be more robust and solid feeling upon opening, due to the thicker FRN on one side. The Goddard and the newer Delicas don't have this feeling.
AUS-8 and G-2 do well in pool environments, whilst ATS-55 rusts too easily in the water (I do rinse them off well in tap water after swimming, though).
I just think the older versions FEEL better in the hand, at least for right hand use. Obviously, for left hand use, the switchable metal clips are better.
I prize my older Enduras and Delica. They are also as tight as can be (even my original, which has been abused through the years!) in both verticle and lateral play. Practically none at all.
Karl