Apart of a little higher energy consumption, I don't think there are other downsides with disabling hibernation.
With modern disks (and average lifetime of appliances
) there is no issues with leaving a disk
spinning idle, provided that temperature stays under control.
Certainly you can first try to disable hibernation, and see if it solves your problem.
If you are using your NAS also for something else, then you can later try e.g. to set hibernation to a longer time,
and make it so that some other, less pedantic, NAS client would always happen to 'wake up' your NAS before any
attempt to access from the Sonos.