Jdnan, I understand what you are saying and I can see that happening with my daughter's band concerts and graduation. Seeing that the L glass does hold it's value well is great news and I don't mind spending the money on it when I save up. I noticed that you are shooting full frame, so would the 85mm be as useful on the cropped body?
My camera is not actually full frame, the 1Ds is full frame. Mine has a 1.3x crop factor, which is still a pro body, but primarily desinged for speed in action situations (10 FPS). This in essence gives me a 110mm medium telephoto. With your camera body, it would be about 135mm. I find it to be a very nice lens, & the focal length is great for me, but of course it's a luxury that you may not want to afford. The price is just so reasonable (around $400), it focuses extremely fast in low light conditions & takes great pictures under all conditions. You would have to decide if the focal length is something that would be appropriate for your needs.