It's not a direct answer to your question, but don't fall for the L-series marketing hype. When shooting with a digital crop body such as the T2i, you may be better served with a good EFS lens.
I have a 70-200 f4L and it's some of the best glass that I own. However, my EFS 17-55 f/2.8 and my EFS 10-22 get great results with my 40D.
This site is a great resource. http://www.the-digital-picture.com/Reviews/