Border boxes are exactly like the ADB border boxes, so yes, mostly cruisers and frigates.
It looks like I'm going to get all three fleet boxes and a Romulan squadron box, and the Romulans will then donate the Kestrel hulls back to the Klingons, will give me 17 Federation, 19 Klingon (with 4 D6s and 4 F5s), 17 Romulan and a spare Condor.
I then just wait for the Klingon/Orion set (22 Klingon) and whenever the Romulan Eagle set gets released (to take 11 Eagle hulls to 16). I may get the Fed new hulls squadron box, and see if removing the aft hull warp pylons from the dreadnought leaving just the dish pylon/engine and the engineering section gives me a passable USS Centigrade.
But will we be playing games needing more than 20 ships a side?