Maybe I've been lucky, but I've had keyboards with hard drives for more than ten years and never had one go out, including X1, SD1, SD5, Midjay and now Audya, plus several models of Yamaha.
Is there a reason you are particularly worried about the Audya hard drive?
Of course all your data can and should be backed up, and I never go anywhere without a contingency plan if any part of my gear should fail. I either have a backup keyboard or at least my laptop in the van if I need it.
One time I FORGOT to load my keyboard and arrived at a job almost 100 miles away. It was the only time I ever had to do a job with midi files and a laptop, but I don't think anyone really noticed.
DonM