Keyboard to play in shoulder strap, this model was released two years after the LN-4. I bought the equivalent of 760 euros in 1990.
Some fully assignable controls: two knobs, two switches, one knob and 10 buttons to program.
In principle it works on battery, with just one MIDI OUT. I changed mine to get the power cable from the midday history to avoid extra batteries or a wire to the leg. It works nickel.
You quickly get used to the touch which is quite comfortable using the shoulder. The weight of the keyboard is like a guitar, about 4kg. The ergonomics promotes a perfect access to controllers that can be assigned with great flexibility to control MIDI, controller, SysEx, etc ...
There are some very interesting specifications such as 8 dynamic curves of the keyboard, the button "panic" ("all sounds off" and "all note off" on all channels) as well as safeguarding the different configs in patches, this which is ideal for the stage.
The manual is very clear and well developed.
EMMC said above, changing the batteries to avoid the need for my taste. In addition, a cable to drag behind you on stage is enough.
For my fans of 80 years, it does.
Among the users: Jan Hammer (signature model), Herbie Hancock, George Duke, Jordan Rudess, Stu Simone ...
Some information about www.synthony.com / vintage / lync.html