Yamaha's Reface DX is a nice little machine - we reviewed it back in 2015 . And while it certainly had a great sound, it suffered from the same somewhat impenetrable programming interface, though to be fair considerably better than the original DX-7 or other Yamaha 4-operator synths of the time.
DTronics - who also make a 150 control programmer for the DX-7, have jst announced their DT-RDX programmer for the Yamaha Reface DX.
Its got 41 knobs and 9 switches with access to all parameters, making FM programming a great deal more hands on. (It makes a huge difference - we hooked up a Behringer BR-2000 in our review and it really opened it up)
50% discount for Sonicstate visitors too