Just FYI, JVC is replacing my second bulb after a year with it and only 378 hours. I will say they seem to be standing behind the projector. That said, a total of 520 hours on two bulbs is really terrible. They need to provide free bulbs to 2,000 shours.
I did have to argue with the technician when he said the best he could was offer me a new lamp at a discounted rate. He tried to tell me there is no known issue with the bulbs. I then said, "yeah that's the reason you have gone through 3 different designs - the latest having an entirely new piece to enhance air flow." After saying that and reminding him that the specs suggest 2,000 hours on a bulb, he offered to send me a new one if I could send him a picture of the projector displaying the current # of hours. I did so and a new lamp is on its way. Kudos to JVC.