The OP on this string has reopened an old discussion. Therefore, I'll repeat myself (actually, the Instructor/Coordinators at the FDNY EMS Command Academy), that the scoop type stretcher does not provide support directly under the spine.
Others state that no pressure on the spine is a good idea. I am not into the research end of the biz, so until the medical director, and the NY State DoH tell me otherwise...
By the way, I seem to recall that one can transport a patient on a scoop to where they can be placed onto the long spine board, and the combination is allowed, but I'd probably be "writ up" if I left the patient on the scoop only, on top of the wheeled stretcher.