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.