Re: Bokken - from the spine or not?
As far as I know, it is a matter of learning stage:
As a beginner some schools and teachers recommend starting from the spine, this should assist you in learning larger sword movement and align your movement to your center.
"Practical" sword cuts start from above your head, each ryu has it's own kamae version, from horizontal sword to perpendicular. Cutting from the spine is not recommended at this level since it is longer (more time) and tends to distort your stance (make you lean backwards).