I don't know how much its a Holy Grail as opposed to just being a good argument in support of an ID and a conundrum for pro-evo's to overcome
Unfortunately irreducible complexity ignores redundant complexity which renders it less than a conundrum.
I assume you are referring to Behe's Blood Clotting Cascade and Kenneth Miller's refutation on that as not having to necessarily have to do with intelligence. I have to disagree with that and I feel that the 'evidence' compiled had more to do with circular reasoning than it did anything else.
No, I'm referring to
redundant complexity.
As for your last bit, I'm not sure what you mean. Are you asking for an example of something that could not have come about by random, successive copying errors?
I'm not asking for one here since it would be massively off topic. However, if you could demonstrate something that could not have come about using the mechanisms described by the theory of evolution then the theory is either in major trouble or has yet to discover an important mechanism.
I almost started a thread on it about 8 or 9 months ago, so if you want to discuss redundant complexity in more depth, I might be convinced to propose a new topic.