>What I'd like to do is shoot for removing the non-free BIOS and then later
aim higher and go for a 15.6” laptop not based on th x86 architecture.
ARM would be perfect for this.
Outstanding performance/watt (especially the ARM A15), ever increasing
GNU/Linux support (Ubuntu 12.04 above works great on ARM) (& much more
supported and well known than MIPS), and no reliance on a BIOS (or at least a
proprietary one).
The only real issue would be 3D acceleration, for which most ARM devices rely
on non-free firmware. I believe I saw an article on Phoronix about a project
liberating at least one of these GPUs, so the situation only seems to be
improving.