While I am very familiar with the arguments for the extra security on the multisig from increasing the signatories numerator, at the moment, I believe that the marginal security gained from this higher threshold (7/9) is outweighed by the marginal utility gained from lowering the threshold to 6/9. Our council is extremely diverse in regards to origin. The advantage of this diversity is that there is a lower probability of collusion (note: I am a council member and therefore you should verify this on your own - don’t take my word for it). The disadvantage of this diversity is that we’re fragmented across many time zones, which results in the need for nearly 90% of viable-signers to be responsive given an emergency. This is because the majority of us are in the 8 hour UTC+2 to UTC-6 range while at least one of us is operating in the UTC+8 to UTC+12 range.
A vulnerability is somewhat of a tail risk and in general we should not change policy simply to hedge tail risk. However, there are other reasons this increased usability would be beneficial in the first year of the DAO. As you all know, our treasury operations are ramping up and we are beginning to execute time-sensitive transactions relating to diversifying our treasury. For this reason, the added utility of a lower signatory threshold is certainly noticeable in its impact and should result in us having better execution.
As we evolve as a community I believe we should gradually increase this threshold and even consider adding members to the council. However, at these early stages, I am advocating for this change.