They do have another linux friendly laptop that can upgrade to 16gb, though its name escapes me now...
Oh, here it is, the M3800:
http://arstechnica.com/gadgets/2015/03/review-dell-m3800-dev...
Oh, here it is, the M3800:
http://arstechnica.com/gadgets/2015/03/review-dell-m3800-dev...
Typing to you on a XPS13 "Early 2015".