It's basically for private/personal usage, almost no concurrent jobs ever, but I don't have the entire day to wait for builds. Doing maybe 10-12 builds per day on average. Storage won't be an issue, it'll be networked from outside of the box, but I'm curious if there is massive difference in performance between M4 Pro and M3 Ultra. FWIW, I'm mostly doing Rust builds at the moment.
Meh, if I'm buying new hardware, (and I'm not that price sensitive,) I'd rather go with the best CPU the model has available when I get it. And no, just a whole bunch of Rust projects, so no compiling of Chromiums, just compilation of other Rust browsers.