According to my convo with mobilenvidia, the M5014 doesn't have a "JBOD" setting per se', but setting a single disk as RAID0 is supposedly nondestructive and leaves existing data alone. Needs more testing, because it must be marking the drive somewhere and I want to analyze which sector(s) if so, to determine impact on pre-formatted drives.
Assuming it works out then this is pretty significant because for close to the same cost as an M1015 you're gaining controller based spindown (power saving) which the M1015 does not support - a big deal for Windows users running software based non-striping pooling/parity like Flexraid or Drivebender+SnapRAID and had to sacrifice spindown to do it with an M1015.