In fifty years I think I've only ever seen one break. Not sure what the circumstances were, but it was an oddity rather than anything remotely common.
Maybe some of the hardcore users here have had more experience along those lines. Basically though there is little to no stress on them naturally. Things really have to tweak, the suspension has to be pulled out tight (and the shock not limiting the down travel), or the clamp itself has to be deformed to be under some kind of pressure.
So not a lot of opportunity for failure.
I could not really see what you were talking about regarding the previous pictures showing a difference in how the clamps are holding the springs though. Or was it the spring sitting slightly skewed?
Was the skew after you twisted and pushed to get it off the tower metal?
Paul