About the ideal size and security concerns: We've actually seen the most pushback from very small teams (5 or less engineers). I'm not sure why exactly, but my best guess is that as companies grow, it simply becomes more normal for them to give access to these tools and they see that nothing bad happens (they end up getting a lot of value actually).
However, we can't integrate with the self-hosted/enterprise versions of GitHub, VS Code/Slack, etc. yet which is what our potentially best customers in the future use.
Because of that, the ICP is engineering teams sized between 15 and 150