Hi,
i've checked my archives for PRS-Customizer (Universal-Flasher 2.x) and sorry there is no such file.
IIRC PRS-Customizer just packed some modified files and replaced the originals in the firmware - simplified speaking.
But PRS+ is still in Google Code Archive.
(If you get a 404-Error enable all scrips if you are using noscipt or similar, this did the trick for me.)
You can find PRS+ 2.0 "LeChuck" for 505 in Downloads at page 2.
As long as you are not using any of the "games/apps" you should be good.
If you do - worst thing that can happen is, that you will have to reset/restart your reader.
And with PRS+ you can set the date/time format to your liking.
If you are not happy with PRS+ you can always re-run the uninstaller you already got.
And remember, there is PRS+safe-mode: If the reader is started with the USB-cable connected to a PC, PRS+ will not be loaded, and you will have - temporary - the stock firmware.