Just to clarify what you all mean in your posts about the relative strengths of offense and defense you build into your ships, can you comment on this example from an actual situation I had in a game. Dark Avatar.

Relatively early in a game, you find that your techs allow you to build either of these fighters as your prime warship for approximately equal const and time to build: A 0-15-0 ship with harpoons and no defense. A 0-9-0 offense and 4-4-4 defense ship with harpoons and defense against all three types of offense. Both ships have medium hulls with 20 hit points. Assuming that you don't have a very good fix on what offensive types the alien ships are going to have, but just as general principle, which would you rather build? Can you explain in terms of what happens in combat why you would select one over the other? How do hit points figure in when you are considering adding defense to your ships?

Thanks. Some very good information in this thread, much appreciated.