This was common practice in the later swingarms. It was a cost saving change as well as a way to stop the "mechanically challenged" (how's that for political correctness?) from having their swing arms seize up through lack of maintenance. The plastics don't last as long BUT they don't chew up the steel bushings/collars, etc. Some guys CLAIM to be able to feel the difference between metal and plastic bushings but for most people it's a moot point. Go with the brass/bronze but make SURE you grease them regularly (at least twice a season-more if you live in a wet climate and ride a lot) and make sure the grease gets to BOTH sides when you put the gun to 'er. Do that and they'll last a LONG time.