I wish the 24-70mm had IS and little more on the short end (like 17 or 18 to 70). I would be sold then. I plan to pick up the 17-55mm f/2.8 IS USM. It's only for crop bodies, but I don't see myself upgrading to a full frame a long time.
You should tell your friend you lost the lens That's a great piece of glass and I would have a hard time letting it go.