Since I am already using High-Priority as my "Star" workaround, it made sense to use other priorities for workarounds too (Using them to actually indicate hard-coded priorities is something I thankfully got away from since using GTD, or rather my own flavor of it).

Since doit.im - as most other digital GTD solutions - has no good implementation yet for separating out Action in projects that are not yet truly actionable (the old parallel/sequential project debate), I found using Low Priority as my separator for non-next actions to be quite useful.
As I set up a project and add tasks, or as I go through my reviews, I try to identify tasks in my project that are not actionable yet, e.g. because they depend on preceding tasks to be completed. These Actions are getting Low Priority. I can now filter these out and only see actionable tasks.

2 disadvantages:
- Manual effort in assigning and maintaining the appropriate priority
- I can't filter only the Next list, thus getting e.g. scheduled tasks in my Filter result, which I do not want to see. I'll add a Feature request to include the list in the Filter criteria.

Otherwise, this works nicely for me.