One thing I remember when fact checking the handbooks against the housebooks was that there was HEAVY summarization done in the handbooks.
A page of info in the housebook was a paragraph in the handbook, if it was even noted at all. Paragraphs were a single sentence.
In short, the housebooks are invaluable if you are a roleplayer, if you want to learn about the universe. If all you care about is the board game, they are basically useless. But if you enjoy the fluff, if you enjoy finding out what political situation caused the Kentares Massacre and the eventual failure of the DC invasion of the Federated Suns, you will LOVE the housebooks.
:)
The handbooks are cool, but they are a candle standing next to the flamethrower that is the house books when it comes to pure information. :)