Thanks for posting! From a ten thousand foot non-expert perspective I always sort of assumed there wouldn't be much extra challenge to editing multiple genes at once relative to editing a single gene - if you're deploying something to go in and make edits to every cell on the body, why can't it make more than one edit? Or failing that why can't multiple editing agents be in the same treatment? Interesting to read about the practical challenges and solutions. 

I live in New York and have been lurking on this site for a while (plus reading HPMoR of course). This post has inspired me to try to get involved with the NY rationalist community. What is the deal with how the community actually functions? How are often are there meet ups? Other basic, boring but necessary questions?