I did a test with C1 LE, Camera raw, lightroom, and DPP. I don't have the tests any longer but I can tell you that C1 won hands down as far as processing raw files. What I was doing was to process the same raw file in the programs at their default settings. What I found was the C1 processed files looked sharper, cleaner, and just looked better. What was really interesting was when looking at the files at 600%. You could see how the program handled a girls eyeliner. In all of the programs but C1, the pixels that made up the eyeliner were black and some red. Also when looking at the skin at 600% I found the individual pixels to be of many different colors. The C1 image, the pixels did not differ untill the skin tone did. The pixels were much more uniform in C1, and at first glance, it would seem that the C1 image would not be as sharp, but they were sharper.
I can say this as to my test and what I found. I also do commercial work for a national magazine. When I displayed the tests I did to the studio manager, (I also did the test on some products I shot) he saw the difference and made the switch to C1 Pro for the magazine.
As to the diference between C1 le and C1 Pro. With Pro, it is basically like using EOS Capture. It also does have a few other differences as far as color profile settings. If you are looking for a program in which you can be tethered to the camera and shoot to your computer with, then Pro is the way to go, but it costs $499. If it's just a raw converter you are looking for, I'd go with the $99 Le version. I will say that it could use some help while editing and sorting images. What I do is use Bridge to edit and sort my images. Once I'm done with that, I use C1 to process the images.