Souping raw files is my main time eater too, but I think a faster SSD will be third to ram and CPU horsepower. I have used my 512GB i7 16GB for a day now and while I love it, the fact I could double my onboard storage and increase write / read speeds by 30%....?....that is something that needs to be known before ordering one of these new laptops, that is actually a huge number for a spare $500!
I think the big difference in speeds has been somewhat hidden in this offering, this site does too for that matter:
http://www.thessdreview.com/daily-n...taining-lesser-performing-sandisk-128gb-ssds/
Regardless, OWC seems to be working hard at offering 3rd party solutions some time next year but in what time frame and at what price? Likely not cheaper than going the Apple BTO route and it is hard to say how close they could get to the theoretical max of PCIe's 1,250 MB/s any time soon.
So I just initiated a return for my 512 and ordered the 1TB using an edu discount, I forgot that since I teach workshops a couple times a year that I could do it so all told it will cost me about $300 to do the swap and be done with it. Now I can keep my 100GB Dropbox account folder synced like I do on my MacPro among other things, should have just gone 1TB in the first place, lol!