I'd say definitely go on the offensive. The starting systems on this map are extremely porous and easy to attack, with homeworlds right next to the star and just about every planet open to attack. You should be able to get a foothold in their star systems relatively easily and move for the kill from there.
The central system is tempting, but defending on this map is so impractical that your best defense is a good offense. With pirates enabled, there's really nothing to be gained from colonizing the central system. You might get some mileage out of leaning on starbases on the stars, but I wouldn't go there.
Given that the stars are readily accessible, you can lean more heavily on support cruisers and carriers on this map than you would otherwise be able to.
Sorry for the lack of paragraphs, something is up with the forums right now.
