The purism devices look fantastic. Does anyone have one and can recommend / !recommend them?
Also the OP asked for 4 cores, the U-range has just 2.
You can install coreboot on other machines, there will still be closed source microcode in the CPU and closed firmware in some of the controllers.
And the hardware is simply out of date, you can get a dell xps 13 with more modern hardware for the same price and in essence the same level of assureance.
If you are worried about state level actors exploiting bugs or backdoors in your hardware Librem isn't what is going to stop them.