Hardware After Effects and Media Encoder 4K + VR

Well, let's begin with the obvious:

in not too much time?

I'm afraid that doesn't make any sense on any level. Without knowing anything about the exact structure of a composition, any statement to that effect can only end up being useless nonsense. Sorry to be so blunt, but you can make AE slow to a crawl with a single effect, if only it is computationally intense enough and dealing with 4k and 8k panoramas and even larger source footage files isn't going to be a walk in the park one way or another. The file I/O alone could be a bottleneck. Likewise, most of your other considerations are moot at this point - AE barely uses GPU acceleration for rendering (though grapevine has it that this will be considerably pimped in the next release), sequentially writing to clip files has limitations on multithreading and so does using effects like Trapcode Particular that use linear progression to do their magic. Hence going crazy about Xeon systems or even dual processors is not really relevant - a lot of the cores will have nothing to do and you'll turn green with frustration on long renders. You simply need to understand how AE's rendering works in the first place and how it uses resources (or not). there isn't a single knob you can turn nor a single isolated hardware component that determines AE performance. Even maxing out RAM may not be relevant at all, since otehr factors will be more critical. You need to take a holistic approach.

Mylenium