,,,, I'm on record as saying I have them and apart from not sinking over time,,,,
That was one reason I looked in to them so long ago (in the late 80's) and spent some considerable time trying all kinds of things to get them to work (on the front),,,,
However,,,,,
As many of us don't drive them daily an we all have trolley jacks, a suggestion I give to slow down the sag / sinking is to slip the jack under the front and lift the wheels just off the ground when not in use (can do the same at the rear, but I've found they don't sag nearly as fast as the fronts). They last shed loads longer,,,,
It's just a matter of getting in to the habit,,,,,,