I guess it comes down to implementation. The S912 boxes varies a lot… memory speed, heatsinks and whatnot. Maybe the best S905X3 box is indeed better than the worse S912 box, who knows.
I’d be interested to know how the S905X3 fares in Hi10p 1080P software decoding. Is it capable of it?
On the topic of the S912 being one the worst chips… that’s BS and you probably know it. The S905 (I had a Odroid C2 with it) that came before was effectively half the speed for almost anything, and let’s not forget about the S80X family that some super lowend boxes use.
edit: Take a look here: Is Hi10p playback OK with CE on NG Boxes? - #11 by jak
There goes the argument that the S905X2 is even equal in performance to the S912. It can’t handle Hi10p 1080P software decoding smoothly, let alone with margin to spare as is the case of the S912.