OK, good luck!
I have spend some additional time on the LR issue and I get an error: "garodclfilter error : 3000" in the driver panel when printing (From LR).
I have re-installed the driver -- ensuring nothing else was running -- rebooted the computer. The issue seems to be related to not being able to make the settings in my driver config (via LR) to "stick". Popular fixes for that error include unchecking the "Fast Graphics Process" checkbox when configuring the driver. I can uncheck that and save the settings but going right back into the driver and it has reverted. There was an indication, in LR, that perhaps the print resolution was too high as well, so I set it to 300 ppi, still failed.
In the end I do know the plug-in worked just fine first try for me.
UPDATE: Its all working now! I went through the process of removing the driver (before installing again) and this time it worked. So...remove the old printer driver before installing the new one (System Preferences -> Printers -> highlight the printer and hit the "-" sign at the bottom of the list)
(BTW, I am sure you know that but I am putting it out there for completeness.)
Hope this helps...
--Jeff