Oh, definitely boost the heroic portion itself. Between shields covering fleet ships and a large amount of drone spam from modules, there's already enough stuff flying around on-planet. The chance to skip would be good too, at 25% you'd have 1.5% chance of getting an all-frigate wave
I'd say 50% minimum, and I might even stretch to double. If we regard one battleship as 1/3rd of a Mk. 5 H/K, then we've gone from 3 H/Ks per wave to about 0.5. I'm fairly certain that, say, a technologist raider would give me considerably more grief than 1/2 a Mk 5 H/K every 20 minutes or so. Again, I'm current sitting at 530 AIP on diff 9. I'd expect a bit of a harsh response, just maybe not in a 'every single wave can wipe a full 2 spire city fleet' kinda way.
Huge grain of salt here though, I haven't played without superweapons of some sort since ... 3.xx days?
Apropos of nothing, just had a wonderful benny hill moment. 10k CPA, of which 7k hits one of my lesser defended chokepoints (I really need to clean up my entry paths). Spire fleet warps in 30 seconds later, and they run to the next planet. And the next one. And the next one. In the end I think I chased them across 6 of my practically undefended backwood planets before finally killing the last one. Always nice to have a little light relief after a grindy week.