Yes this is the one you will need for the new SX series.
Hi Eileen,
this new YEM version is NOT only for use with the new PSR-SX series:
There are also some bugfixes from YEM v2.5.2 to v2.5.3, and EVERY user of a YEM-compatible keyboard (Genos, Tyros5, PSR-Sx7x, PSR-SX) should always use the latest version of YEM.
P.S.
Please note that the old YEM version MUST be DEINSTALLED, when using WINDOWS (not needed on macOS).
Best regards,,
Chris