the preferences from 14 to 15 were copied ok with 3 exceptions as far as i can see:
beautifier rules
custom keywords
autoreplace

they all have "14" in them, e.g.,
C:\Users\<username?\AppData\Roaming\PLSQL Developer 14\Preferences\<username>

I think they should all be copied. We'll check it out.

plugins were also not copied

key bindings for plugins not copied at installation of beta5 even though they were active in beta3

+1.
My key bindings were also lost from beta3 to 5.
Attempting to import them from an ini file from V14 doesn't apply them.
Setting them in the beta5 Config window doesn't work when I try to use them in a SQL window.
This has made beta5 unusable for me, whereas beta3 worked very well.

BTW, I installed the 64-bit version on Windows 10, if it matters.

We'll check it out. Can you provide an example of a SQL Window function key that does not work for you?