Well, it's been about a year and a half, and now, my SX-50 bulb is noticably dimmer. My Canon LV-X1 bulb I previously owned lasted about as long. A new one's is coming in and we'll all see the difference. The 'meter' for the bulb is about two thirds across.
I also hooked an HD-DVD player to the SX-50. Though the image was sharper, the difference was just barely discernable on our 10' screen, especially in contrast to the region 4 DVDs I have.
I think, until they actually stop (or if they they stop) pressing standard DVDs, the HD/Blu-ray will be an incidental market, like the Laserdiscs were 20 or so years ago. I don't have much interest in it, it seems a very few do. Standard DVDs with the right equipment, can look nearly as good!