Nope, no DroboS, I'm just an information "offender".
There's lots of examples of hardware or software that may not be supported by current (or recent) macOS versions, but that might work anyway. The only problem with THAT, is when you have a problem that requires you to set up as a new device (or to reinstall the original software), and you can't get it working again. Good example is some close-to-classic Adobe suites. I have a good friend who was using CS4, and continued to update his Mac to El Capitan. CS4 is not supported, and hasn't since maybe OS X 10.8 or .9 (not sure), but his software continued to work, until some weird files started to be produced, and my friend had reinstalled CS4 several years ago for a similar problem. Well, this time, the uninstall/reinstall did not even try to work. CS4 blew up/hiccuped/burped/vomited - however you want to express it - it doesn't work now, unless my friend reboots to a a Lion system.
Anyway, long story. The point is, if you have an older hardware, then it might work for you, but you don't have much recourse if it decides not to work, and you might not know even what causes it, or when it stops working (not good for a backup system, eh?)
You COULD upgrade a test system to Sierra (with a good, complete backup in case something goes wrong, as you should do with any production software upgrade) It could be on your main drive. Use it for a few days, and see what happens.
Finally, as this site is relatively low traffic, you might ask about droboS on another Mac forum site that has much more possibility to find another user who has a DroboS. I also like MacRumors.com forums.
