Rosetree, perhaps you could contact the performer for that video clip of the S910 https://www.youtube.com/channel/UCvRDxVLogHRDaQMlKQAoplA and he could give you the details?

I don't have access to an S910 to experiment with the RH keyboard section being split into two sections, although I'm pretty sure that it is possible...it's also possible to set each RH voice to mono individually with different portamento rates/octaves/effects etc., but I'm sure the competitor's arrangers also have similar features..

I very nearly bought my demo S910 (I liked it more than the subsequent model, the S950), but I was offered a great deal on a Tyros4 upon my retirement, so, of course, I took it immediately. The S910 is a very powerful arranger, which, unfortunately (through my experience as a former clinician) is rarely used to its full potential by most users.

Of course, we might say that about arranger users of all brands, not just Yamaha. In any case, it pays to dig in and learn the instrument's full potential, rather than trading up every two to three years just for a few new features and perhaps some newer styles.

Ian