> It seems to me that running https://tails.boum.org/ inside a VM would be much more trustworthy than a browser bundle from this point of view. Even other barely-sensitive stuff like computer model or screen resolution will be better hidden inside a VM.
Things like screen resolution, installed fonts etc can add up to quite a reasonable way of tracking when taken together; see https://panopticlick.eff.org/
You're right a VM would be a way to combat this, but it would take a lot more resources, be harder to get right cross platform, and certainly push things way over the nice 25MB limit. Better would be to have a firefox addon which just misreports this stuff, and maybe regularly changes it, as you're getting at above.