It seems like such a long cue would make it difficult to keep the tip down during follow-through (too much weight in the rear).
I stopped by Mike Gulyassy's booth at SBE this spring and asked him about Earl's outlandish cue. He asked if I wanted to take a look at another one that was almost the same as Earl's. I was very surprised at how nice it felt in my hands. The balance felt perfect and Mike said it hits great as well. It didn't feel butt-heavy to me at all, or even heavy in any way. The shaft was as smooth as any I've ever felt, and Mike said it was a proprietary finish that he was using that was responsible for that.
Of course, I can barely swing a 58" cue in my cramped basement without hitting the wall, so this will always be just a curiosity for elite players to me.