I would recommend retooling the AI's use of Gauss Def Plats or buff up the Gauss platform firing range (a lot, double it).
Eh ... that would really dampen the Frigate though, they don't last very long against the gauss platform, the platform packs a powerful punch and double their current range meaning there will be little to no room for the frigate not to get fragged. Maybe adding a new platform with longer but a weaker punch for these kind of things, but double the range of the guass platform is a no go IMO.
Next, full system colonization is pretty easy and I get -85% HPD penalty only if my Capitol is on the far side of the system. The other 2 solar systems are still being developed by the time my economy is smoking, fleets are running rampant and victory is only a stone-throw away.
The AI right now doesn't do a lot of expansion IMO, especially toward un populated system so most of the time the only force stand between you and your own ship is the local pirate, which easy to wipe out.
I also noticed that Cap ships now level up MUCH slower than Beta 1 but still pack quite the punch once researched fully. Researching them fully is expensive but the Cap ship cost isn't. For now this favors the player over the AI since the player starts cranking them out (like in beta one) and can easily mow down any enemy opposition.
I agree, they're still too cheap, too easy to build and build too fast right now. Although the AI problem is more like the lack of the coordination, they have ship but only move them from what it seems random movement in small groups, sometime even individually between planets without a specific attacking pattern. In fact, the only one doing specific attack right now is the pirate.