Kirk
With Capitan 10.11.3, no folder in preferences, only :
com.camerabits.PhotoMechanic.LSSharedFileList
com.camerabits.PhotoMechanic
com.camerabits.PMNavigationAgent
Nothing in Application support
PM would not be able to operate without losing all of your preferences if the com.camerabits.PhotoMechanic folder and the files contained therein were not available.
I'd like to see a screenshot of the Finder window displaying the com.camerabits section of your home folder's Library/Preferences folder. Or if you feel comfortable using the Terminal, enter:
ls ~/Library/Preferences/com.camerabits.PhotoMechanic
Then copy and paste the results in your reply to this message.
-Kirk