This implies you'd run more than one Mac Studio in a cluster, and I have a few concerns regarding Mac clustering (as someone who's managed a number of tiny clusters, with various hardware):
1. The power button is in an awkward location, meaning rackmounting them (either 10" or 19" rack) is a bit cumbersome (at best)
2. Thunderbolt is great for peripherals, but as a semi-permanent interconnect, I have worries over the port's physical stability... wish they made a Mac with QSFP :)
3. Cabling will be important, as I've had tons of issues with TB4 and TB5 devices with anything but the most expensive Cable Matters and Apple cables I've tested (and even then...)
4. macOS remote management is not nearly as efficient as Linux, at least if you're using open source / built-in tooling
To that last point, I've been trying to figure out a way to, for example, upgrade to macOS 26.2 from 26.1 remotely, without a GUI, but it looks like you _have_ to use something like Screen Sharing or an IP KVM to log into the UI, to click the right buttons to initiate the upgrade.
Trying "sudo softwareupdate -i -a" will install minor updates, but not full OS upgrades, at least AFAICT.
I have no experience with this, but for what it's worth, looks like there's a rack mounting enclosure available which mechanically extends the power switch: https://www.sonnetstore.com/products/rackmac-studio
"... Thunderbolt is great for peripherals, but as a semi-permanent interconnect, I have worries over the port's physical stability ..."
Thunderbolt as a server interconnect displeases me aesthetically but my conclusion is the opposite of yours:
If the systems are locked into place as servers in a rack the movements and stresses on the cable are much lower than when it is used as a peripheral interconnect for a desktop or laptop, yes ?
VNC over SSH tunneling always worked well for me before I had Apple Remote Desktop available, though I don't recall if I ever initiated a connection attempt from anything other than macOS...
erase-install can be run non-interactively when the correct arguments are used. I've only ever used it with an MDM in play so YMMV:
With MDM solutions you can not only get software update management, but even full LOM for models that support this. There are free and open source MDM out there.
They do still sell the Mac Pro in a rack mount configuration. But, it was never updated for M3 Ultra, and feels not long for this world.
> To that last point, I've been trying to figure out a way to, for example, upgrade to macOS 26.2 from 26.1 remotely,
I think you can do this if you install a MDM profile on the Macs and use some kind of management software like Jamf.
It’s been terrible for years/forever. Even Xserves didn’t really meet the needs of a professional data centre. And it’s got worse as a server OS because it’s not a core focus. Don’t understand why anyone tries to bother - apart from this MLX use case or as a ProRes render farm.
There are open source MDM projects, I'm not familiar but https://github.com/micromdm/nanohub might do the job for OS upgrades.
For #2, OWC puts a screw hole above their dock's thunderbolt ports so that you can attach a stabilizer around the cord
https://www.owc.com/solutions/thunderbolt-dock
It's a poor imitation of old ports that had screws on the cables, but should help reduce inadvertent port stress.
The screw only works with limited devices (ie not the Mac Studio end of the cord) but it can also be adhesive mounted.
https://eshop.macsales.com/item/OWC/CLINGON1PK/