I don't currently have a backup keyboard with me at my jobs though I have had two keyboards in my stage rig in the past so if one went out I always had the other. I've never had a failure on stage so the extra weight/effort never seemed worthwhile and I now only use one keyboard. However I do have several backup systems at home that I can use in case my main keyboard was to need repair. Since a lot of my stage music is in midi files and in the Yamaha XG format, I have now loaded the S-YXG50 soft synth onto two laptops and one desktop. I have a variety of keyboards I can use with the laptops, or I can use an existing acoustic piano.

I wouldn't mind having a spare 9000 Pro though when the right one comes along.