Reference weight and the upper arm :-
Having removed and stripped and then destroyed one, I can safely say it has no structural strength whatsoever. Nor will its mounts offer stability in the forwar/rearward plane of movement.
The safety factor of the ball joint protruding through will offer safe guard for the 3 bolts coming undone, but not alter in any way the inherent strength or turning moment about the pin.
Therefore it should considered very carefully before being done as the ball joint could fall away if the bolts come un done.
I and everyone I have seen with them done have gone to lengths to ensure this doesnt happen by use of nylocs etc.
The Calmini and other replacement arms do not have close units to retain the ball joint. These bolt the ball joint as in a ball joint flip with only the bolts to retain it and as such should be monitored.
As for all mods to all cars here, they are done and advised over at the end users personal risk, but then as the advice is all free it comes with a full money back guaruntee
just my 2p