http://www.dpreview.com/reviews/canoneos600d/17
You can selected different cameras to compare. NEX-5N vs T3i vs T4i vs Olympus OM-D E5.
Then, you can move the focus areas to see the differences.
Olympus OM-D with ony 4/3" size sensor is actually doing better than most of APS-C size sensors regardless mirrorless and dSLRs. The only area is not good is its video performance.