Thanks for the suggestion. I primarily went with the B version as it's available at a local store. I was able to find the version you're suggesting for only slightly more, however it looks like it only has PCIE X1 rather than X16. The Perc H310 SAS card I have is X4 I believe so won't fit in the J3455 board.. And while M2 is nice, it's not something I can see myself needing in this nas.
Thanks for the suggestion though.