We still have the same Chamberlain opener that was installed when we bought the house in 2006 but it has some new parts. The main drive gear is some sort of polymer and it shredded itself when someone tried to open the door when it was frozen to the floor, so I had to replace it. Then, 4-5 years ago it stopped responding to the remote so I had to replace the circuit board and I was lucky enough to find a used one on eBay or cheap.
My advice is to install a good surge protector for your opener just like you would any other piece of delicate electronics because that's what usually kills them. My dad went through openers like a wino through Boone's Farm and it was never a mechanical issue that killed them. It was always the circuit board getting fried because he was at the end of a poorly-rmodulated supply line. I think it was a near-miss by lightning that zapped mine.
While you're at it, put a surge protector on your refrigerator and any other major appliance that has a circuit board.