Plastic drop links have been the way to go for a lot of different manufacturers for several years, either in the ball joint, the actual link or both! Thing is some of them haven't got any cheaper by being plastic. Some are better quality than others as with all things! Vauxhall ones are crap, for those that tend to bounce up & down kerbs they have a nasty habit of snapping the link as the suspension bounces!
Got one to fit to a zafira this morning, this guy just doesn't learn, it's his second one since xmas!
As for Jedi's, the links are good quality, but the ball joint sockets are POO! crap plastic & dry! maybe the mexicans just can't make plastic? Though Jedi did get told by Dave that the IRO ones are mega money & exactly the same part, so be warned if your tempted to go that way!