I can literally hear your excitement as you describe your new camera!! It is making me want to upgrade even more from my T3i. I do have one question for you. Are you saying the ISO 800 is about the same as 25000 in JPEG or RAW?
I too am about to upgrade to the 5D3 and considering the price. The photos posted above look impressive. The 5D3 at 6400 seems to have slightly more noise than the T3i at 1600. The various tests I've seen seem to indicate that the 5D3 has 1.5 stops of improved noise performance. The noise performance is the same at 1.5 stops increased brightness via ISO increase.
What is harder for me to tell is how this will translate to real world performance. Since beyond just noise, the overall IQ of the image produced is supposed to be far superior. So a bit more noise on a much clearer image may well look MUCH better in real world shots... or not. I do not ever shoot in jpeg so the noise reduction that the 5D3 does in jpeg mode is irrelevant to me.
I'd be interested in the answer to LibertyRanger's question. In RAW, in real world scenarios, what is the equivalent quality wise on the 5D3 to the T3i at ISO 800 & 1600.
Thanks all!! This will be very helpful to me in making my final purchase decision. The price of the camera is significantly outside of my comfort zone but I need a pro body in order to get the work I want to do.