Does OSX support SMR hard drives

No experience with it myself, but others appear to be working with them. So I'd say: yes. 🙂

http://forums.macrumors.com/threads/what-are-the-options-for-10gbe-on-mac-pros.1 959937/

As far as I can see the really low level stuff like SMR is totally hidden from the view of the computer operating system so the answer is yes it will work. Similarly whether a drive is a new Helium filled drive or not is something totally invisible to the computer and does not cause a problem.

Factors more likely to affect a computer are sector size and capacity, originally drives had a sector size of 512bytes, higher end bigger capacity drives now have a sector size of 4096bytes aka. 4K. This actually causes no problems to Macs but older versions of Windows do have problems with this. With regards to capacity, some older drive controller chips - which would be built-in to the computer may not support larger capacity drives, again in general this is not a problem with Macs but some external drive enclosures have problems with drives bigger than 2TB.

Finally there is a an issue with the screw holes on newer bigger drives i.e. 6TB or bigger. These have shallower screw holes so that original longer screws are too long, also some newer drives have the holes in different positions, both these issues mean it can cause problems fitting them in Macs.