I can see one potential benefit to having the lathe bed - and
motor - behind the work rather than below it.

That puts more mass BEHIND the axis of rotation rather than
below the axis of rotation. That seems like it would provide
more resistance to wobblin' & walkin' when working with "out
of round" pieces.

As for turning while seated, I personally want all the spatial
options I can get should things go bad. Being spacially
constrained concerns me. Just the logistics would bug me
- stand up to put a chuck away and get a drill chuck, get up
to sharpen a tool, get up to pick up the whatever I dropped.
And having Swing and Sway movement restricted would be
a bit irritating very quickly.

I have to take my hat off to woodworkers in wheel chairs.
They often make the rest of us look like slouches.

Interesting set of questions - as usual.

charlie b