I thought I actually intentionally avoided CV for Corvette because it would clash with one of the Aircraft Carrier designations. But I may be confused about the ultimate conclusion I was able to derive from that navy site...
And I use CA for cruiser instead of CC
The DN designation is indeed ambiguous if one tries to derive it from history, so I'm actually using it in the Harrington/Lensman/etc sci-fi sense. There it means a whole new "displacement" range after BB. Similar with the Imperial Spire SDN, which you only see at the very end of FS.
Anyway, back to less important matters like game design
I kept the +0.2 modifier for champions because I didn't have time to try to do a full-orbed overhaul of the champion-counter into the nemesis system. The nemesis stuff is
only to prevent the human from assassinating the AI HWs via champions+minions (+ whatever, though I'm not aware of anyone getting supply on the AI HW in order to drop a modfort on its head) without taking any planets or otherwise at least "activating" the AI's response via some significant degree of AIP.
I'm quite happy to add an offensive component to the nemesis concept (I'll leave those particular ships where they are, except for perhaps rebalancing their numbers), the simplest of which I can think of is to just directly reinforce the Threat Fleet, which will come after you wherever it thinks it has a chance.
A more direct counter is to have a separate coherent "anti-champion" fleet that does stuff like camping nebula wormholes with grav, tachyon, forcefield coverage, and a lot of stuff with bonuses vs structural and heavy. And keeping a rapid-response force to go after the champion whenever it's spotted in AI territory without a big escort. Making something like that out of a copy of the special forces / threat fleet logic would be pretty easy. But would you actually want it to do that? Sounds like it could be a bit frustrating for someone who just wants to cruise around in a hero ship in addition to their AIW game
On the food-metaphor bit: base game + champion + nothing-else should absolutely be fun and balanced, no need to add minor factions. If it's not there, we need to get it there