Yes the SB are overpowering, if you notice 4 per sector I can set it so most of my planets are within range of 8 bases, that's 400% Research/econ/industry per planet.
THis corner setup was actually pretty good, it's like the computer knows you are stuck in the corner so most of those planets were pq14+ from the start. Also I used the minor race as my trading partner, all my freighters passed through the range of all my bases hehehe. If I had time I would have put military bases on the outside rim where my ships are, spaced out perfectly.