Just bought this for my SX900:https://smile.amazon.com/gp/product/B00C4VTCZC/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
You'll need to reverse the polarity of the footswitch (in the kb menu) to use it.
(Yamaha is normally closed)
It's solid, QUIET and has dedicated 1/4" plugs for each pedal.
I use one for damper, and one for harm on/off.