Except the performance has not been tested enough in the wild enough to garner any actual useful information.
Not much mystery:
The M1 Max version performs exactly the same as the M1 Max MacBook Pro.
The M1 Ultra version just has everything doubled up, so if your workflow scales with the number of CPU and/or GPU cores you can pretty much predict how it is likely to perform.
The GPU is amazing for a truly mobile GPU, OK for a desktop-class GPU but nothing special
unless you're running software that is well optimised for Metal, uses the media engine, neural engine etc. Big surprise - Apple picked benchmarks that show this off, and if you're using the Studio for what it is good at they're probably representative.
The Studio will be at its most impressive when used as an "appliance" for running FCPx, Logic, and other MacOS-centric applications. For cross-platform applications, 3D modelling etc. they'll probably turn out to be "meh".
I can't imagine that anybody is actually deliberating whether to buy a Studio versus getting their
first Intel Mac Pro (people will still need new MPs for replacements, new employees etc). Even current Mac Pro owners probably got them because they had a pre-existing workflow - running on Rube Goldberg Trashcan/PCIe-enclosure lash-ups or geriatric classic cheesgraters - which they weren't prepared to change.
The question is what the new Mac Pro that Apple have teased will look like. It's hard to see how they could produce something directly equivalent to the Intel MP with the M1 technology seen so far. The rumoured "quad" M1 Max chip would, presumably, max out at 256GB RAM - which isn't going to satisfy those who need the current 1.5TB - and switching to external RAM would erase some of the M1s speed advantage over Intel. Doubling the CPU and GPU cores
again could see a serious case of diminishing returns. We don't know what the PCIe capabilities of the M1 are (it obviously has
some PCIe lanes for Ethernet, SD etc.) or if it could hope to support the number & bandwidth of PCIe cards in the Intel Mac Pro. Everything that Apple has said so far implies that support for third-party GPUs is dead and, again, U-turning on this erases some of the efficiencies of having the GPU on die. Some users still need PCIe for specialist audio/video interfaces etc. but maybe
that can be satisfied with a Thunderbolt PCIe enclosure (...Thunderbolt has sped uo since the Trashcan days).
Possibly Apple might have to cede the market for 1.5TB RAM, Quad top-end AMD GPU monsters to the PC world (...after all, no NVIDIA is already a problem there).
The
minimum for a new Mac Pro might simply be a M1 Ultra system in 1U rack-mount form, with matching rackmount PCIe cages and storage units available. Or, maybe, M1 Max/Ultra modules in MPX-like form that could plug in to a proprietary MAC-Pro-like enclosure.