Well, I can't say as I've read the book or anything, but the idea that the doomsday machine was built to fight the Borg really doesn't make sense. I've always felt it was, as the name suggests, a last effort to defeat some ancient enemy that has continued to operate. I mean, if the only way to kill one is to fly a cruiser sized vessel into the maw and blow it up, then the thing wouldn't last very long...the Borg would have no trouble sacrificing a cube to end the threat.
As for the comment about Lucas and SW, I feel that at least SW continuity makes more sense. Sure the novels may have paid a little, but the movies and "canon" facts are more in keeping with what we have seen. Why? Because B&B don't work for SW.
My $.02