That's what stood out for me about all the StationX except for the Spitfire: they have nVidia GPUs. Having dicked around with nouveau and nvidia/dkms with various nVidia chips I will never buy anything with closed-source/binary-blob. It's just not worth my time.
You don't get a line of laptops off the ground overnight. AMD/ATI linux drivers not sucking is a fairly recent development. If were making this decision ~5 years ago, Nvidia would be a reasonable choice.
I spent about $1000 on a Sager 6 years ago, and was very happy with it (including the Nvidia hardware; it was tough to get running in Optimus mode, but works well now).
Last year it had a spate of corrupted video output, with red static all over the screen. Went on for about a week, and I bought a new laptop...then the problems with the Sager disappeared. All well. I think it's still the most maintainable laptop that I own.
* Except for the Nvidia hardware, which never really worked right. I'm using unaccelerated (?) Nouveau drivers as the least bad option.