I agree completely that the DSII shouldn't have been built so fast. I personally hold that the Empire was actually building it shortly after the construction on the DSI had begun. But other than that, I do think they're comparable. I mean no disrespect (in spite of my snotty previous comment--sorry), but the Borg cubes were just as frightening as the Death Star to me. A single cube was sent to assimilate earth. Of course it failed. So what did the Borg do? They sent another single cube to assimilate earth! Yet I love The Best of Both Worlds and I love First Contact. The reason being that the stories are well told in spite of repeated elements.

Building a second station is logical in many ways. Look what the US is doing. We're nearly done constructing new World Trade Centers, i.e. new prominent terrorist targets.

The DSII wasn't the most original idea for ROTJ. But in my opinion, it wasn't really that bad. The stakes did need to be raised, and I personally have yet to really enjoy any of the other superweapons existing in the Star Wars universe, except perhaps Centerpoint Station which was large and required massive amounts of power, was still vulnerable (e.g. no stupid Sun Crusher armor), was stationary, and destroyed its targets in a different method. Every other superweapon idea throughout the EU was honestly just plain stupid.