I am in the same situation. I can't decide between Lenovo Thinkpad and Dell XPS 13/15 Developer Edition. This happened because I came across the HN discussion and saw a lot of people who recommended between those. Then, I just saw this discussion.
Actually, I have been deciding to choose Dell XPS over Lenovo because its security (I am still doubt with that and need to read more). I heard that Lenovo laptops have backdoor/SuperFish installed, is that true?