I only run 10.7:1 with a DCR of 8.33 and a tight quench in my Mustang, the truck is 10.0 with a DCR of 8.2 and a bit looser quench. Neither of them have an issue and every street engine I build gets a PCV. Granted, I have not had the opportunity to build 12:1 street engines though
FWIW less than 1000 miles on the truck engine, but the Mustang has been together, both in carb'd form and EFI since late 2006 and is as clean inside as it every has been. It's got just a basic set of Mahle moly rings with a low tension oil ring set in it too
Keep in mind, the PCV certainly can pull vapor in, but PCV vacuum is high at light load, and low at high load, and near zero at WOT. So really the most vapor flow would be during the conditions least likely for detonation.
In fact, unless you have a blow-by problem or a lack of baffles, I have not even seen evidence of oil in the intake plenum, now if you have a blow by issue, then that needs to be addressed more than the PCV IMHO.
Of course, as Jay said, it's cheap and easily undone too, so worst case, take it back off.