I was somewhat surprised to read that the 1MW unit will actually be hundreds of the demo units working in tandem. Why, do you think? Because Rossi has been unable to control the process inside a considerably larger reaction vessel? Or, and this is my uninformed guess, he doesn’t have the capital required to develop a large device but hopes to get sufficient funding if he demonstrates he can reliably provide 1MW of power using his proven 50ccm units.
I think this is precisely why. If "self-sustaining" without the external "tickle" current, it tends to "run away".