Good advice here as always. I'll be short and sweet and say that the 70-200mm f/4L IS is one of the finest lens' I've owned. I now use the 70-200mm f/2.8L IS II, I only upgraded because I needed the extra couple of stops of light when shooting weddings. I have used the non-IS version in a limited capacity but I wasn't nearly as impressed with is as the IS version. If it were me, I'd save up/ shell out a few more bucks for the IS version. It's an excellent lens.

I don't have the T3i but I did have the 40D and here's a couple of old shots with the IS version. This first one was pretty heavily cropped. The third was with extension tubes so I'm not sure how relevant it is but I don't have any others on my flickr page with that lens.

Hope this helps a little, although it doesn't entirely address your OP.

Ben


Bush Canary (found out what it actually is) by Ben__Taylor, on Flickr\


First Aiders by Ben__Taylor, on Flickr


Rawr!!! by Ben__Taylor, on Flickr