Masswineguy,
The 500 hours is a rough estimate based on my personal experience. But I certainly luv the Quad dynamic speakers. You would be hard-pressed to find a competition in their range that can do music better. I have mentioned in my posts before. The Quads were never in my shortlist when I wanted to put together a good system. But one listen to the Quad 12Ls and I was hooked. I went back and researched on the difference between 12L and 21L and came to a decision that I wanted the floor-standers. I got the 21L sight unseen, sound unheard (though familiarized by 12L).
And look at it this way - either 11L or 12L you are gonna have a winner :-) Oh, I am so waiting to get my audio room back :-(