I came across this great (well great except for the language barrier) video that compares the 5D MKII and RED ONE cameras. Worth noting: this video comparison is before the recently announced 5D MKII firmware update that now incorporates the manual exposure everyone has been asking for. It's the dynamic range of the RED ONE that is so very impressive. The first time I saw it being used I was blown away!
Here's the video, and this is an article with excerpts translated to english.
And because I need a photo, here's my sister Rachelle when we ate Onikoakoa. So good! Thailand photos will be up soon.