I somehow missed these posts light night...shouldn't post when feeling sick
Lights can surely be good anytime - but thats for a pillager...
... I have had 1.3M light units and 500k elites units and it did miracles. But I wouldnt try it if I wasnt a pillager
I agree that much changes as game progresses, lots of other factors will come into play. But for R63 which is fresh into the heavy phase for most players, these are moot points. The current field here is 5-15k points, 20k +/- units total, so the original question and my comments pertain a clear state of few thousand of light vs heavy soldiers. And yes, we're talking v4a - don't know how this translates to the other versions, but something is screwed up with lights here.
jams was messing with you ...
all spears have a 4x bonus against cavalry, but because heavier .cavalry have more resistance and attacking power, they will naturally resist more efficiently to lighter spears ... but that doesn't mean they are immune to it, quite the contrary at high attack and armor tech values
heavy cavalry is stronger than light cavalry - fact
heavy cavalry cost more than light cavalry - fact
on a attacking power/ressource cost ratio, heavy cavalry seems less interesting than light cavalry - fact
on a practical basis, which troop is more likely to win a battle : heavy cavalry - fact
Unless I'm terribly mistaken (or there is some hidden armor value for heavy cavalry), it's the light units that gain most from the attack and armor upgrades. Lets compare 100 Spearmen vs 60 Heavy Spearmen (same cost/networth when built).
at 7 melee
100 spearmen damage = 100 x 17 = 1.700
60 H.spearmen damage = 100 x 22 = 1.320
28,8% more for light
at 12 melee, just before Elites
100 spearmen damage = 100 x 22 = 2.200
60 H.spearmen damage = 60 x 27 = 1.620
35,8% more for light
The theory, calculator (I've already given examples for h.cav) and practice are much against the facts you state (at 7/8 upgrades):
100 Light Cavalry = 4.700 damage, 40.700 hp
60 H. Cavalry = 4.020 damage, 36.420 hp
The higher individual HP helps heavier units survive better in some situations, but as soon as armies grow above 1000 soldiers of the type, it becomes pretty much irrelevant. I have a fairly large army and kill record and I've tried substituting heavy units for the lights in many of the battles I've done (in the calculator) and pretty much every time lights have come out better. Especially as you say, in the most common case of one sided battles IO is designed around. I still fail to see how exactly heavy are better? (and tbh it pisses me cause I was looking forward to them)