Actually, on further recollection, Steve Omohundro and Peter Cheeseman would probably count as academics who know the arguments. Mostly I've talked to them about FAI stuff, so I'm actually having trouble recalling whether they have any particular disagreement with me about hard takeoff.
I think that w/r/t Cheeseman, I had to talk to Cheeseman for a while before he started to appreciate the potential speed of a FOOM, as opposed to just the FOOM itself which he considered obvious. I think I tried to describe your position to Cheeseman and Cheeseman thought it was pretty implausible, but of course that could just be the fact that I was describing it from outside - that counts for nothing in my view until you talk to Cheeseman, otherwise he's not familiar enough with your arguments. (See, the part about setting the bar high works both ways - I can be just as fast to write off the fact of someone else's disagreement with you, if they're insufficiently familiar with your arguments.)
I'm not sure I can recall what Omohundro thinks - he might be intermediate between yourself and myself...? I'm not sure how much I've talked hard takeoff per se with Omohundro, but he's certainly in the game.
I think Steve Omohundro disagees about the degree to which takeoff is likely to be centralized, due to what I think is the libertarian impulses I mentioned earlier.
As promised, here is the "Q" part of the Less Wrong Video Q&A with Eliezer Yudkowsky.
The Rules
1) One question per comment (to allow voting to carry more information about people's preferences).
2) Try to be as clear and concise as possible. If your question can't be condensed to a few paragraphs, you should probably ask in a separate post. Make sure you have an actual question somewhere in there (you can bold it to make it easier to scan).
3) Eliezer hasn't been subpoenaed. He will simply ignore the questions he doesn't want to answer, even if they somehow received 3^^^3 votes.
4) If you reference certain things that are online in your question, provide a link.
5) This thread will be open to questions and votes for at least 7 days. After that, it is up to Eliezer to decide when the best time to film his answers will be. [Update: Today, November 18, marks the 7th day since this thread was posted. If you haven't already done so, now would be a good time to review the questions and vote for your favorites.]
Suggestions
Don't limit yourself to things that have been mentioned on OB/LW. I expect that this will be the majority of questions, but you shouldn't feel limited to these topics. I've always found that a wide variety of topics makes a Q&A more interesting. If you're uncertain, ask anyway and let the voting sort out the wheat from the chaff.
It's okay to attempt humor (but good luck, it's a tough crowd).
If a discussion breaks out about a question (f.ex. to ask for clarifications) and the original poster decides to modify the question, the top level comment should be updated with the modified question (make it easy to find your question, don't have the latest version buried in a long thread).
Update: Eliezer's video answers to 30 questions from this thread can be found here.