Jack,
Thanks for the feedback and update. I'm planning to visit Focus-on-Imaging at the NEC near Birmingham on Monday, and I'm hoping to get some feedback there. (Expect I'll be lucky!)
Having had a 1D Mk III for around 2 years, and am probably still getting to know its CFns' foibles etc., I'm fairly sceptical that any journalist can jump from one make to another and write a review which does anything more than scratch the surface of these vastly capable and complex machines. For example, I went to a local Pancake Race two weeks ago and came back with my worst set of images in years! I did better last year...
The polythene wrapped magazine I bought two days ago proclaimed on its cover that it was reviewing the 1D Mk IV and what did I find? Just 3 pages of report, and no images on the CD. Silly me, I bought this quite expensive rag on trust thinking that at least they would have copied their test images to the supplied CD, but no, that was taken up with yet more videos of how to use Photoshop. At least with just 3 pages of report, they didn't dig deep, and came up with a fairly bland recommendation. For items costing around £4,000 I feel we need better and more informed advice - it's no wonder that the internet seems to win out in these areas.
Given more time, I expect the news and comments about the 1D Mk IV will settle down, and I'll have more idea whether it's a sensible spend for my type of shooting.