You'll prolly be cool with the Whiteline endlinks. After I broke mine, Whiteline offered to send me a free replacement, and told me they were working on increasing the strength of the materials they use on 'em. I told them thanks, but I need 'em ASAP and couldn't wait for them to ship from Australia, so I just ordered from KartBoy w/ overnight shipping.
Hopefully, they've upped the strength of their endlinks since then... after all it was at least a year ago. Another thing to think about
: if something's gonna break, it should be the cheapest part of the suspension. I'd hate to bend a swaybar or control arm after hitting a curb 'cause the endlink was so g'damn beefy. In fact, a lot of the WRX rally teams use the *stock* :shock: plastic/rubber endlinks so they *will* break before the more expensive stuff. You can easily swap a tanked endlink at a service station in your 20 minutes, whereas replacing a swaybar is much harder, and replacing a control arm (while not ruining the alignment) is damn near impossible.
Besides, if a rear endlink goes, you car won't spin, it'll just be come very plow-happy, so it's not too unsafe. And Whiteline's customer service is AMAZING... the president regularly posts on NASIOC, and I guarentee they'll send you a new set, all you gotta do is post a picture of your broken link and wait for the Australian mail service.