I love the sound in the JV1010 session board, and you can get that for under $400 US. Give a listen to the Yamaha P80 - weighs in at about 35lbs or so, and has great piano action. Forhet that RD600 - it's a bear to tote around and the buzz on the street is:
It's not long for the world. Wait till the NAMM show in January - see what springs up.