Richard Jones, whose blog Soft Machines I read regularly and recommend enthusiastically, replied in the Moot:
Unlike Dale, I am a molecular scientist (a physicist, to be precise) and I have extensively engaged in technical discussions with enthusiasts for molecular nanotechnology (see here, for example); after spending quite a lot of time doing this I have, from a different starting point, come to the same conclusion as Dale, that the essence of these arguments isn't actually technical at all, but ideological.
It's not exactly sport, though; there's no professional reward for doing it, and it gets wearisome and time-consuming. For this reason, very few practising nano-scientists do get involved (an exception to this is Philip Moriarty -- see this long correspondence). In a way this is unfortunate, because I think that many enthusiasts for MNT are genuinely unaware of how strong the scientific consensus is against their ideas.
One of the reasons for the difficulties of these conversations is that some of the most vocal proponents of MNT (with some honourable exceptions) aren't as familiar with the basic physics, chemistry and materials science background as they should be. To be fair, it can be difficult for those outside academia and without access to the technical literature to keep up with developments (this is another strong argument for open-access publishing, of course [hear! hear! -- d]), but sometimes it seems as though some MNT enthusiasts' main source of science understanding is from reading and reproducing press releases.
There's maybe a difficulty of tone, too -- I've been accused of being occasionally disrespectful or disdainful to my interlocutors. There has sometimes perhaps been some truth in this, which I regret, though I claim in mitigation some provocation (for example by the not infrequent suggestion that I'm arguing in bad faith). But it does suggest to me that these communities don't have the same traditions of robust self-criticism and vigorous argument that science at its best does. I have to say that my reaction to some of the moans one gets about how unfairly MNT supporters are treated in some of these exchanges is to think to myself, these are people who've never seen a set of referees' reports from Physical Review Letters or Nature, or been at the receiving end of a rough bout of questioning after a conference talk on some controversial science issue. Proper scientific discourse does have some robust exchanges, and you need this if you are going to avoid group-think or wishful thinking.