Just decided to try taking the pirate base, at the end of a 9+ hr game. took a maxed out fleet of 6 lvl 10 caps and about 260 frigates, 150 of them LRFs, with all military research completed. I managed to take out about 1/3 of their ships, and didn't even touch the 20 or so turrets.
Pirate stats at this point:
Corsair - 7392 hull, 42 armor, 167 ac damage (50 exp)
Cutthroat - 5616 hull, 40 armor, 130+43 laser damage (35 exp)
Rogue - 4608 hull, 38 armor, 103 ac damage (15 exp)
Pillager - 4176 hull, 37 armor, 136 laser damage (30 exp)
Reaper - 6360 hull, 40 armor, 214 ac damage (25 exp)
Defense Platform - 16800 hull, 50 armor, 134 gauss damage (50 exp)
Numbers: 23 Corsairs, 7 Rogues, 8 Pillagers, 16 Reapers, 13 Cutthroats
There were also about 35 more ships out raiding one of my planets at the time I attacked.
Just counting what was actually at the base when I attacked, they had a total of 729658 hull points. My orkys had about 21000, so that's the equivalent of about 35 fully upgraded starbases in one gravwell, in terms of defense. Possibly more, actually, because the ships have more armour than my starbases seem to get. If I could be bothered to calculate the damage I'm sure it would be in a similar area.
Just in case anyone was curious but didn't want to play a massive long game to find out!