@dfort: Ah, Gotcha that makes sense! Please continue to play with @Danne's incredible app/service workflow since it works really well for most situations and it actually does all the dirty work as well as organizing files into folders for you. Just simply laid back and enjoy a cup of tea while you're at it or sleep overnight with ease!
Well I am glad you are still hung on using Dual-ISO -- it's one of the best features for ML of all time and definitely takes time getting used to but you're getting closer!
Strange that you managed to get this plugin to work again after downgrading/upgrading the exiftool because for me it was rather strange and I knew I shouldn't have tried fixing what's not broken, right? lol
Anyway so on my MBP after updating the exiftool to the latest and tried running LR5 again with the plugin which now is popping up windows saying "Please report to ML forum. An internal error has occurred: Failed to find a place for the imported file" in which I have tried both with original and new folder but neither worked. I'll have to investigate further why it works on Mac Mini but not the MBP.
and on top of that it's even more odd that both of the Beta3 20-bit plugin's are showing different options to choose from in between my MBP and Mac Mini.

On the MBP it isn't showing the option to choose "KEEP ORIGINAL DNG AFTER CONVERSION" but it does on the very same plugin in Mac Mini, strange?
p.s. Yes, both are running the latest OS X (10.10.1) in case you guys were curious.