In the states they arn't allowed,
I've looked into using them (rose or heim joints) in extreme steering arms (top and bottom captive

) but I couldn't find anything in the Low Volume cert online legal'es, that dosn't mean its not there

I have enough problems with english with out throwing all that in-direct talk in there
I'd talk to your local certifier and see what they have to say at the end of the day its there "interpretation" that counts (and I've noticed it can vary

)
Just a couple of pionts your not going to get much more range of movement (depends on the brand) your still looking at around 30deg same as most balljoints, the other issue is your going to have to machine these bolts from hard steel and this is gona cost... or if you run doouble captive

way stronger !! your arms will cost a mint, as they're not allowed any welds now

but they'd be as cool as hell
Hey if you get the go from your certifier let us know
Cheers Reece