I've read the whole thread and I agree with Ron and Gary.
Devices that won't boot the software that the user chooses are traps and should never be bought. Even devices that let the user control the keys they trust are regrettable. The only solution would be a massive rejection of the whole scheme.
On one hand I doubt the security of rejecting unsigned code is worth turning a gerneral purpose computer in a machine that will only run a finite set of software or will run untrusted software with restrictions. It's like havign less of the general machine you meant to buy.
On the other even if we keep our freedom to run what we want we have already lost the freedom of running what we want without others being able to know what we run (in fact being able to tell we don't run what they trust). For now secure boot only restricts what we boot (and the booted OS restricts the rest of what we run). But in the end the purpuse is to stablish a DRM scheme so that if a server can't prove that we're running software trusted by them (not us) then we won't be able to access content or even we'll be refused connection to the internet or whatever has to do with equipment controlled by someone else.
So yes, the only solution is, as Ron suggested to plainly reject the scheme, to avoid buying, running, working around these sort of restrictions. And still this is only useful if the majority of people does it. Then the providers of internet access, connectivity or whatever we want of others won't find interesting to restrict their business to the few secure booters. I'm not so optimistic about how feasible this is now and how feasible it gets each day.
Intel CPUs are sold in equipment with intel GPUs. Intel GPUS have free software drivers, but Intel did not provide code or documentation to boot their CPUs (does it now ? at least Google paid for some free code so it's better than it was, right?). Modern Intel CPUs need to run signed, propietary code before they can even access RAM.
AMD contributes code to coreboot and documents their processors well. But then their GPUs (wih computing power and acces to main memory, etc.) run some form of propietary code (even with the free software drivers). And I heard their lates GPUs don't even have good support in this kind of free drivers with propietary AtomBIOS. And the tools to implement secure boot are there too, so once everybody runs secure booted platforms people may be able to tell we're not.
Likiwise new ARM processors are getting TrustZone and similar technology (and often require propietary drivers for GPUs).
I haven't heard so much for MIPS, but I haven't heard of similarly powerful MIPS processors either.
So our choices are not very nice, even if some choices are nicer than others.
My impression is that we're headed to a world were there'll be open hardware plataforms, running free software and accessing more or less free content, and mainstream closed hardware running nonfre software and accessing DRMized content. With little or no bidges between these worlds. And hardware does not have the same economics of software, so being a niche market can be harder than when free software and propietary software could run on the same hardware.
It's a pity, but people aren't protesting enough.