The stock rockers hold up pretty good for me. However, I changed it to aluminum since I am going to P2 rockers anyway.
Whatever you going to buy, don't get the 3Racing's crap. No to mention they won't fit properly!
Integy made some nice rockers so you might want to check them out. If you are too darn rich, take a look at Hardcore Racing's, which I think not necessary because aluminum would last for a long time.
Yup! boiling plastic parts will make them last a bit longer.