It is very easy to edit sounds on the X1/X4. Just push the edit voice function key and you're there! At this point you can change filter, envelope, LFO, etc. and then hit save/enter and you can save your sound. The 8000 and 9000 keyboards are the same action, and as Fran said the X1 is semi-weighted. The keys look just like any other 61 note synth keyboard, but if you feel under the key you will feel a glued in weight. This is what makes it semi weighted. The selling price for a X4 will vary because there will be 4 different models offered. If you want prices you will have to contact one of us dealers directly. I don't quote discount prices on this forum. This forum is primarily to discuss topics and ask questions about keyboards and the way they work.
George Kaye
Kaye's Music Scene
Reseda, California