I haven't heard any rumours I'm afraid.
RGS made themselves very unpopular when they ran a late entry test four years ago in similar circumstances. (These two schools always seem to be playing push me pull you).
The late, curriculum based test was comparatively easy to pass by all accounts and the ratio of pass/fail told a similar story, but of course not every body heard about it and not all that did felt prepared with the short notice. They did mop up a few of the near misses though, but obviously that was also denying the effectiveness of the original 11+ test and the appeal system for recruitment of the correct pupils, so highly contentious.
I hate the fact that some schools set their own 12+ that is truly 100% curriculum/subject based, when the candidates vary from attending top flight independent schools to failing uppers.
Not fair at all imo.
However I do know several 12+ successes, from Indies and a few from upper, so definitely worth a bash.