I've only just started using warheads so I suppose I'll get used to using the features with a high cost when the situation does demand it.
Also, I do think there has been a major increase in wave strength recently... tried going through the wave logic and logging last night to see if I could see the cause. Either way with multiple HW starts the first wave is 2-4 waves with 4 caps of bombers each... by 5h I was getting 4k ship waves at 220 AIP, ultra-low caps, 4 HW start. Snake map so 1 ingress point bonus 2x, AI type gives another 3x I think, gets x1.5 from bonus from reinforcements... had to use lots of warheads to stay alive before dying or even being able to really start the fallen spire cities. cross planet attacks are still tiny though