The sample Canon 5D-II vs Nikon D750 photo you linked to at
Cometh the 5D-S R down the isle.... - FM Forums
shows a deliberate underexposure recovery test. The 5-stop underexposure software recovery of the Canon 5D Mark II shot is
literally filled, across the entire frame, with God-awful, patterned, color noise that utterly ruins the photo for professional use. The Nikon file is pretty usable, with no trace of color or pattern noise.
But it's not just about underexposing a shot by five full EV--the practical aspect is that with a modern Nikon, a person can expose to protect the highlights from blowing out, and can then make what were formerly, literally IMPOSSIBLE shadow recovery adjustments in software. Without the strong pattern and color noise than Canon has been plagued with for years.
Hey...8-track tapes were once considered perfectly good. But eventually CD-ROM came along. Same fundamental problems: sticking with outdated technology means that eventually, your company **is behind** the leaders, at least in some ways.
Part II - Controlled tests
Anywayyyy, threads like this really don't do much except inflame Canon system users. I still have a little bit of Canon stuff around, my 5D and 20D, 70-200/2.8 L IS USM, 135/2-L and 135/2.8 Soft focus, but have sold off the 50/1.4, the 580 EX-II, 24-105 L IS USM, and 85/1.8 EF lenses. I shot the 20D two weekends ago with a photo student of mine, and was shocked at how narrow the dynamic range of the RAW files was on a bright sunny day. I know the 20D sensor is old, and outdated, but what I am used to with the now-old D3x and the first-generation SONY EXMOR sensor it has has now been beaten by yet another full EV worth of DR by the newest Nikon bodies.
Canon still has some great lenses in its systems, but I think the real nugget is that for the wedding shooter, the amazing shadow recovery, low noise at high ISO, and the sheer "workability" of these files from the newer Nikons means much easier file processing, and also easier shooting, with MUCH less absolute "need" for using fill lighting in fast-developing situations over 3,4,5,6,7,8-hour wedding shoots.