I don't think planets are going to work as the “slingshot effect” thing that you put at the center of the map. The way the planet is working now makes me see that for it to work as a slingshot the planet is going to be a size that modern gamers think is silly. Most of the ships would be bigger than the planet. I think the best thing to do is to start thinking of a planet as an obstacle with light gravity that can be at the map center, interfering with slower ships ability to control the center on maps where a planet is present.
For the slingshot effect, just mention somewhere in the lore that “micro-singularities” are common in the SCO universe, tiny little black holes. Then it makes perfect sense to everyone that there is a tiny little dot at the center of the map that has the slingshot effect. This would be even smaller than Dan'nath's black hole, but I'll talk about that with the Dan'nath ship next week. I can still usually beat most or all of the enemy lineup if I start with Dan'nath, and taking it at any point during a match is like pushing an “I win” button.