macOS X 10.13.1 is out, doesn't look like it's updated the BootROM firmware (it's still MBP121.0171.B00) or SMC, will install on my 13-inch rMBP with 960 EVO and let you know.
Nah, it didn't do anything to BootROM or SMC on Late 2013 13-inch rMBP.
Noted on ghifar's post that he literally didn't need to do any mods other than the adapter itself.
I suspect that this is because the SM951 NVMe is probably electrically similar to the OEM Apple SSD, even down to the firmware; they seem a wee bit more pricey than the 960 EVO / PROs but it might actually be worth it to get one and test it.
Also, since Samsung manufactures many of Apple's OEM SSD's, I'd bet good money the SM951 NVMe might be the best replacement in terms of performance/dependability ratio..