In this discussion, there is an absence of information regarding applications beyond video and editing that demonstrate the performance disparity between the M4 Max and M3 Ultra. There are science applications such as Computational Fluid Dynamics (CFD) and statistical analysis that can run for extended periods (days, weeks, and even months) needing multi-core, memory-intensive, and I/O-intensive. These types of applications prioritize utilizing as many cores as possible, except for one or two, to accommodate small, supplementary processes that require CPU resources. Consequently, they utilize all available memory except for a small portion needed for macOS system requirements and will periodically demand significant I/O bandwidth to create substantial checkpoint files. It is evident that these applications are vastly different from video and editing applications. Nevertheless, the M3 Ultra emerges as the superior choice for such s
NeatBenchcientific-oriented applications. When inter-core communication is critical, memory bandwidth becomes paramount, and the Ultra consistently outperforms its counterpart. It is worth noting that there are numerous other use cases beyond video and editing.
Furthermore, it is crucial to consider the scenario of video and/or editing applications, where numerous other macOS processes simultaneously demand attention and cannot be abruptly terminated. Consequently, having more cores available to service these processes alongside the video and editing tasks can effectively prevent interruptions to video and editing tasks.
BY THE WAY..... If you use Apple's bundled Photos and have the habit of scrubbing through massive number of photo images Photos will grab and use as many cores as it can along with GPU use. Lots of cores is simply good to have for many things besides applications used for video creation and editing.
Just for kicks I wanted to indicate the more cores you have the more work per time period can be achieved.... take a look at my screen shot below, where I have a ChronoSync backup of 4.5 TB in progress, several Safari web sites active, playing a Chess game, have several desktop widgets showing various stuff for quick review, and so on. The cores are being saturated and everything is very responsive, and could very well have a 90 min movie running to take a break from Chess

. The Ultra is a Mac that excels for general purpose and not just for video / editing.
...As an aside.... You can order each Studio model, test them using your 'use cases' and keep one and return the other within Apple's 14-day return policy. There's no reason to be shy about doing this because Apple offers this option for free, except you do have to pay for each one up front.
Just saying ..... OK.

Cheers to all and good luck choosing between these two new Studios.