I'm interested in the M3800 or the new XPS 13 when it becomes available. I'd like to run Arch. I'm not a GNU/Linux guru but I've installed Arch a few times in VMs and I'm ready to switch to Arch for my next machine.
While I don't expect any official support from Dell, does the Sputnik team tinker with other distros during development? Is there any reason why Arch wouldn't work with the Sputnik laptops?
I would check the Arch Wiki and/or Forums and see if their community has any information on your particular model machine.
That page should give you an idea of what models are supported, and if any have known issues that you'd need to look out for. If the specific model you're wanting to use is not listed, it does not mean it's not supported, It just means nobody has reported using it. Check if a SIMILAR system is supported, and judge from that point.