The Harmony-M sounds/works fine with excellent reverb/effects. The price dropped to < half of the initial price and is around € 120,- now.
I bought one to 'isolate' singing from the Tyros4 because the mic input is affected by the main-volume of T4.
Also like the basic user interface (no whistles and bells, screen menu's and countless presets) almost like the Korg iH.