If you take a REAL close look at his hands, you'll see that he plays a bare handful of notes outside the 76 note range. Hardly enough to warrant lugging a big heavy 88 around. If you need a section where your hands DO both go to the extremes of an 88, it is fairly simply to program an OTS to leave a gap in the middle of the keyboard and transpose the lower down an octave.

But take a look at where he is playing, it hardly seems needed. I am fairly confident I could do the same style without needing an 88 and no-one would notice. So much of how we feel about playing seems to come from what we see while we listen. Without that, I doubt that many of us could tell whether he was using an 88 or not.

But yes... it certainly would help him to have a CS, as there's no change in the backing chords at all.

He's a real powerhouse in the style, a great player. But he could quite easily do the exact same thing with just ONE 76...