OK, I’ll give the first part another listen. However, as a new artist to me, I may not be the best judge.
While it may not be easy, just go for it! Ha ha 
I hadn’t been aware of the firmware updates until viewing this thread (thanks to all) and have now updated my NAS333 and Uniti Atom HE.
All working well and don’t notice any degradation in SQ. By the same token, I haven’t noticed any improvement but have yet to have a proper listen though.