I read that the X1 was developed with Intel, and thus they can't use AMD CPUs in that lineup. I don't know if it's true or not. It was a random reddit comment.
I'm personally not a fan of HP laptops, but i'm looking forward to AMD CPUs on thinkpad and Dell XPS laptops. There is no way there isn't going to be a X1 type laptop with an AMD CPU. Lenovo can't leave that kind of battery performance on the table without losing market share to Dell and HP.
But... 20% cheaper. 50% faster in multi-threaded tests, 20% faster in single-threaded tests.