Not quite your dilemma, but I moved from a Unity2 to a NDX/202/200 and then 202 to 282, then 282 to 252/SCDR with a 250 (later 250DR), but this was a while ago so TBH my memory is hazy.
As you already have the wonderful 282/SC combo, I would upgrade your streaming source next (although I will admit I am not familiar with your current streaming source) and the NDX2 is the obvious choice as its performance is on par with a NDS which I currently own too. The NDX2/XPS will get the very best out of the 282/SC.
If at all possible, the usual advice of demoing both options, preferably at home, is the very best way of ensuring you make the right decision for you.