Ignoring for a second that they claim these have the same performance without providing any actual benchmarks that I see... the server configurations alone make no sense. In 2021 nobody would order 12x HP proliants with less than 256GB of memory per server and then run 1,000 VMs on them. That averages out to what? Roughly 2GB of memory per server unless you're horribly oversubscribing them - which nobody who has ever designed a virtual environment would ever tell you to do - so your VMs are going to be memory starved pretty much 24/7. Even IBM tells you not to oversubscribe memory on their mainframes.

I also struggle to believe that oversubscribing the z CPUs 66:1 isn't going to result in performance issues. The documents on limits aren't clear but I foresee that mainframe spending a LOT of time on locks even with all the work IBM has done to help manage them.

This whole thing just really smells like a bad advertisement for IBM, which aligns with them announcing their latest gen z processor last week.