Neutral spine has been around for some time now. It was brought into Pilates by the physio industry after research into multifidi connections for spinal stability, etc, etc.
Joe Pilates never used neutral spine or even mentioned it. So the pilates world has now bent over backwards to accommodate this research into the programs on the floor and reformer and other equipment.
I think this is totally misled as NO research was ever conducted into the effects of moving from neutral spine into forward flexion for exercises such as the Single leg stretch, Double leg stretch, Hundred, etc. and its effects, especially on neck strain – the biggest issue with most people doing these exercises.
Have a look at the attached video to see what I mean and how to solve this issue.