So, I currently have a T2i/550D, and just for curiosities sake decided to look at the noise sample images back to back vs my cam. http://www.the-digital-picture.com/Reviews/Camera-Noise.aspx?Camera=1044&Test=0&ISO=1600&CameraComp=688&TestComp=0&ISOComp=1600
I am really surprised that they are so similar. I mean, in most of the samples, besides the higher resolution, it's hard to really tell which is which. The T2i has one of the very earliest 18mp sensors, I would have thought in the several years since there would be a more notable difference!