I tried this out in a 7/7 game today (with the patch now, but this game was started before that patch if it matters) with FS and Golems on. I control over half the map. It got *goofy*. Stuff like waves of 4000 beam frigates. Well actually more like 600 beam frigates and an army of carriers that flew up to my spire city and started shooting everything without the city shooting back because I didn't change that default. Kind of off topic, but I've been finding a lot of stuff that bugs me in how carriers are working right now.
Now I've just been goofing around in this game and experimenting with new stuff, so it's not set up as well as I'm capable of (and certainly not as well as the experts could do). But still. The sheer number of ships coming out was being measured in thousands, per wave. That included the counter waves
To comment on something you mentioned earlier - turret controllers simply don't matter when 2000 ships show up (as nice as Spider V's are, they don't matter a whole lot against 2000 ships). I actually had four (Spider, Sniper, Flak, Missile), and while they did damage, they're not any serious threat to stop a counterattack wave of that sizes. Plus you're really unlikely to have Spider V's everywhere, because the cost of a cap on a planet is so massive that it'd really lengthen the game.
I also found Golems totally ineffective against these waves. Even the Botnet doesn't shoot fast enough to do much against so many ships, but stuff like Artillery and Armored were just a waste of time. I'd have been better off turning them off based on what I've read here.
Given how if my fleet was in the area (including 2 Spire Dreadnaughts) the game was slowing down a lot against one of these waves, I suspect if I pulled back and refortified at the point where I have a single choke point it would have turned into a slideshow (three of the four showdowns were behind that, I'm not sure how I'd have defended the fourth one).
Comparatively, my Spire fleet was powerful enough that I could have simply walked into the Ai Homeworlds with it and flattened them. Normal AI waves weren't threatening me, every entry point had a Spire city on it, a Fortress II, Millitary Command III and other goodies. AIP was up to 600, and that's after reducing it a boatload using the SuperTerminal (before reduction was I think pushing 1500).
If I can find time I'll try it again in a less "conquer the galaxy" type of game and see how that goes, but based on how it responded in this case I don't think it's an option that's for me. The AI sent absurdly more stuff than it would in response to the FS endgame, and even that wasn't necessary in this game since I could just fly into their homeworld and beat it directly with little risk.