Brilliant. Thank you both for taking the time to reply - appreciate it.
For those who are finding this post for the same reason that I asked the question in the first place, what happens here is that yes, the structure is "destroyed" when you change from flexsection to another format and then back again, in that the structure of the sections/subsections does not revert to how you had it. All the sections remain but what were subsections will be at the top level so will need to rearrange them manually.
As the content remains unaffected, this to me is not a big issue.
Carl
