It's a race between what wears out quicker, the belt or the pulleys. Those QPD rear pulleys are cast aluminum and fairly soft and are certainly not permanent. And the rear pulley is the major cost of the kit. I was quoted $550 just to replace the rear pulley.
So you're probably looking at a complete QPD kit every 50,000 miles, so at best it will always cost twice as much as running a chain.
Now if only someone would come up with a tougher billet alloy based kit, I might reconsider.
