Long before I began using PM, I used, and still use, the period as a separator to set the heirarchy for my catalog program (IMatch). I have almost 20,000 images with the keyword heirarchy embedded (mostly NEF) using the period and I'm not about to go back through those to change it. The period does not cause me any problems (I do not use Adobe products so that's not an issue, although I tried an early version of Lightroom and had no problems reading my current files). When I have some time, I may setup some test files on a laptop to see how mixed files, some with periods and some with the pipe, work together. I'm not going to chance it with my main system until I'm convinced changing in midstream won't crash my whole setup. For now, I'll stick with an older version of PM or go back to ingesting in my catalog program.