I have used some of all of them, and I could tell no difference.. however I don't use the UOA as a tool either. I think if there were any difference to one or the other ( no matter which one better) the UOA, VOA etc tools would have caught it, and BITOG users are fanatics about any changes made to the beloved oil they have chosen to use as the grail of oils... the GC, specifically the green was at least that if not more, and again I have seen nothing in the form of my use, others post, nor via UOA/VOA ( I will admit I have not checked much lately on this) that nothing changed other than the color.. I myself did like the green the bestest by far... but it's only dye.
on edit: I'm not much on telling anyone to use the search engine, because if everyone done that we would have no new post !! However a huge amount of information just popped up when I typed in german castrol green in the search engine.