OK, got it. Thanks for the replies.
In this case, comments alone don't quite do the job. I tend to use comments for references and "why is this here?" sort of commentary, whereas the Scrivener inline annotations are very handy for placeholder text as in "this copy is rubbish, fix this first" or "there is more detail that should go here".
I can use Markdown-style workarounds for this, which is what I've used in other editors (as they're easy to strip out in a hurry with macros), but it would be good at some point to have the ability to have a choice of comments/annotations that go inline and others that can go into virtual stickies.