Great lens - you'r e not going to regret that for one second.
It's amazing how many people think white lenses are some sort of marketing ploy by Canon. I often curse the colour myself as not the most suitable for wildlife.
I was out shooting a few weeks ago though, sat for quite a while in strong sun with the camera tripod mounted. The CF tripod was so hot I could barely stand to touch it, and the camera body was warm - approaching hot to the touch. I have a cammo cover on the lens which was quite warm to the touch, but interestingly the white bits of the lens not covered by the cammo were relatively cool. :shrug: