Dan, welcome to Scuba Board!
That pretty well sums up what divers here have to say about the BH, too.
The only way to know for sure is to do it yourself. Then you'll have an opinion based on your own experience rather than on what other folks are telling you, which isn't that much help since there's such a split.
Five hours r/t to do an in/down/up/out dive where good viz and shark sightings may or may not happen is a bit much. But as Gaz, in an earlier post in this thread, and many others have said, the other two dives in the area are incredible and five hours r/t to do those two dives would be well worth it in my book. In that light, a unique dive like the BH is really just a bonus and not the main attraction.
For me, the bottom line is that even a bad day of diving in Belize beats a great day at the office like a rented mule.
Not that I've ever had a bad day of diving in Belize...
As always, ymmv and there's nothing wrong with that.