Pairing was the practice people talked about the most, because it caused the most friction. I'm not sure that I would say it was the essence of XP -- I think XP was about taking collective responsibility, sustainable pace, and feedback. Pairing was a practice to support those values.

I miss pairing. It is powerful on its own, and is shockingly effective when combined with the whole XP thing. But you can still get a ton of value from the rest to XP even with async comms.