e31 control arms on the e34

I know that it's possible to use the alloy e31 control arms on an e34. How long could I expect the spherical bearings to last (with normal driving) before needing to be replaced. I guess I'm asking if it's worth the price to upgrade as I replace my front end.
-ashley

they work but are a lot more expensive becasue of the bushing you mentioned. there's some pics on bruno's site about it. probably not worth it.