how longs does the spherical bearings last...?

[MaxD]

This is the slippery slope you travel when you go solid/spherical. Once you start to have any play, rattle, it is time to replace.

Same goes for all Porsche solid, tie rods, links, control arms etc.

I've had various spherical pieces last years to one event. Driving on the street kills them quickly.

Suggest NHBB as a replacement - in my hands they seem to last the longest but YMMV.