Jim, I checked out the PS website. The slide-in card Bridge 2 for your DS DAC seems like a no brainer. The ethernet connection NUC > DS DAC will address any shared USB issues. I am no expert on USB versions, but I do not think you will have problems with USB3. RAM should be 8Gb minimum these days, but I would play it safe and use 16 Gb. NUC RAM is cheap (not like Mac soldered in RAM). If you have a problem in the short term sharing a USB DAC and USB backup drive. You can always, backup manually after quitting Roon.
Good luck and good listening.
Jeff
Is this certain? I thought the feature set of 1.2 was scaled back.
Nothing is certain. I believe the devs have said publicly that they expect RoonBridge in 1.2 in a variety of flavours including Linux. We can run RoonBridge on the above devices using Linux. I think you may be referring to bootable images for specific devices, which the devs said might be later.