What do you mean by "lack of a spine"? Muscles? I'd think contour would protect the spine area better than trifecta.
No, the lack of a 'spine' in a pad.
I worry that with a large grippy pad that it will actually put pressure on the spine, with the panels of the saddle kind of stretching across it. I'm explaining it badly.....
You can pull a saddle pad up into the gullet at the withers, and we all do to stop the saddle pushing the pad onto them and causing pressure, well I worry that pressure will occur further back, does that make sense?