Looking at thermionics--doesn't look proven to me. Great stuff if it works, but if it doesn't does the whole nanofactory concept collapse? No, you just have to use some tech that does work, and you should budget for it. There shouldn't be more than one breakthrough on the critical path, that's asking for disaster in a real project. In this case it's asking to be dismissed as an unrealistic handwaver. Given that you put zero as the mass of the cooling system (and other support systems) when calculating the reproduction time for the nanofactory I've still got doubts.
You'll be right far more often if you try to prove to yourself that it will be easy.
I'm not going to take an optimistic attitude looking at this stuff. Optimistic engineers destroyed Challenger and Columbia. Optimistic engineers burned people to death in Ford Pintos. It is immoral for engineers to be optimistic. We are obligated to contemplate all the things that can go wrong and prove something will work safely.
You will usually have to prove it to yourselves.
I'm not taking on the burden of proof here.
Let's face it, Chris, you're asking a lot of us.
You want working scientists and engineers to give up safer career opportunities to work on MNT.
You want investors and gov't agencies to put their money into MNT research.
You want policy-makers to leave off worrying about wars, budgets, and elections to decide how to handle MNT.
They're not going to do it unless they see proof. You bear the burden of proof to show that this stuff can have a real impact. Optimism won't cut it. They'll send an engineer to look over your work. If he comes back and says "They neglect this major factor, they assume that thing has a mass of zero when it's got to be at least 20% of the total system, and I can't see the deployment working at all" you won't get an appointment and your issue will be off their agenda. Right now the deck is stacked against you even worse because we just went through a big wave of optimists saying "trust me, this will work out in the end" and a lot of people got burned.
I'm not asking you to do my "homework." I'm offering you a chance to convince me that the "big step" of exponential production can happen. If you're too busy, no problem, I've got other stuff to do too. But if you can't convince me you're going to have a hell of a time convincing the people you need to convince.