Can it accept a sound module, that is, can it be connected to a device that contains other sounds (or presets)? Is it MIDI compatible? Does it have weighted keys? Are the keys velocity sensitive.
A good idea these days is to buy a controller. This is just a full size, weighted keys, keyboard. It has no sounds built in. You would connect this to a sound module, or your computer with compatible software. This way, it will never be 'outdated'. Whatever new program or sound that comes along, you can INTERFACE with it directly.