>Perhaps its different when you are spending someone else's cash?
No, it's his money; he's the MD of his own video production / motion graphics company. He has done the sums, and is buying one. Since his business has grown steadily since he started it, I'm inclined to believe he knows what he is doing.
>I hope he realises the new Mac Pro maxes out at 64GB of RAM which will put a severe crimp on doing anything memory-intensive.
Not really. He currently uses the older Mac Pros and a 32 GB Hackintosh, and hasn't come close to running into RAM limits. His workflow is mainly video - compositing, editing, colour grading etc - but also ray-trace rendering of 3D models and compositing the results into the above. RAM is just not the current bottle neck, and again, he knows what he is doing.
It is not the machine for me - I'm a PC based CAD jockey. My level of CAD work just doesn't require the extreme storage IO that video work does, and intensive tasks like rendering can be distributed across any CPUs/GPUs across the network.