So can the actual impact of a cap shift actually be more than a 50% reduction or a 100% increase?
Yes, of course (imagine a ship doing 1 damage/second with 1 hp). 4000 of those is a lot more effective than a fighter. But my point was that these situations are vanishingly rare in this game, so shouldn't have a high weight in the balance thereof.
Demonstrably false. Starships prove it.
You may be using a different definition of "large-scale" than I am.
But starships surviving is to be expected. They have a low DPS:HP ratio, so they are fairly low on the autotarget list (as they should be). Skirmishes and raids are where HP and toughest-individual-unit matter.
If you are in a battle where the toughest single ship can die really fast, then the ratios are all that really matter.
Take a ship with 4 hp and 1 dps. The mkII has 8 hp and 2 dps. Cap of 24, say.
Two ships mkI lose to a mkII, with the victor having no losses.
Two caps of mkI lose to a cap of mkII, but just barely. Here's how it breaks down:
Edit: also included the results of 20 caps mkI vs 10 caps mkII:
48/24 480/240
36/18 360/180
27/14 270/135
20/11 203/102
15/8 153/76
11/6 115/57
8/5 86/44
5/4 64/33
3/3 48/25
2/3 35/19
1/2 ...
0/2 0/6
As the size of the battle increases, individual unit strength relevance approaches zero. It is quite close to zero for the whole game, and thus should not be a major factor in balancing.