You have to go back with a GEDCOM file.
You won't loose anything unless you have edited the sources to the new format, or added new formatted sources, they probably won't transfer back because RM3 won't know what to do with those several fields. (Free Form sources or those unchanged after import to RM4 should be ok)
Also, any Place Details will probably be lost because there is no place for them in RM3
OH YES! While setting up the GEDCOM export, be sure to uncheck the bottom option: "Extra Details ( RM Specific)" or your sentence templates will be all messed up. You will be back to the RootsMagic 3 defaults and no sentence templates for any user defined facts.
+++++++
Set your Folders option to keep the data out of Program Files.
Either in my documents or just in a new dedicated folder like "C:\RM-Data"
Is anything in the works for the fix for these errors? I haven't read all of the messages but if I take my file back to RM3, I will lose some data. I'm at a loss here. I'm stressing out with these problems. Any advice?