Yes, the discussion should have been more focused. Otherwise there is just way too much ground to cover in an hour. There was not enough back and forth over the key points. Still it was pretty interesting (given the participants, how could it not be!)

As far as the argument itself goes, I would have made the following points:

1. If we get to the point where practical immortality is feasible, so much else will have changed about the world that it's extremely hard to predict what the impact of immortality would be. When you are predicting the future, it's very hard to get out of one's current mindset. Which is why the clothing in 1960s sci fi television looks very 60s-ish.

2. I don't think there is a choice between immortality and unlimited reproduction. Even without immortality, unlimited reproduction is a problem. Immortality only makes it a bit worse. We don't see the reproduction problem right now because it's only in the last 50 or 100 years that it's become possible to reproduce ad libitum. Right now, less than 1% of the world's population is taking advantage of this opportunity.

3. I agree with Yudkowsky 100% about the silver lining phenomenon. It's too much of a coincidence to think that we are pretty close to the optimal lifespan for the good of society. I would like to flat out ask Brin and PZ what the optimal lifespan is for the good of society. If they don't have a specific range which they can justify, then they are not in a position to reject immortality on that basis.