--- Damage increases runs a serious risk of completely unbalancing these weapons, because they don't exist in a vacuum. Under the damage model, a 5 second 80cm HPM could put out 24 damage versus shields per increment, while a single 80cm Meson could do 8 damage to the enemy hull per increment and potentially send a good chunk of that directly to the internals. And once the shields were stripped or the Mesons got lucky and hit them through armor, the HPMs would swiftly render the enemy unable to fire back. All at a very long range comparatively speaking, since you could rush down Capacitor Tech and Weapon Caliber. And as long as you kept up with your Beam FCS range, this would be incredibly potent.
What I'm failing to see here is how this is any different than increasing the effective rate of fire. If a meson cannon or HPM deals 4 damage per hit, how is that any different in practice from firing four times as fast? I can see minor details like shield regeneration but these are minor, the main effect seems the same to me. The one exception is the ROF 5 limit, which working with damage instead of ROF neatly avoids and I would count that as a point in favor of working with damage.
And if the practical effect is the same then the only point which needs to be settled is the matter of degree, since we can adjust the damage/ROF/etc. scaling as needed until a reasonable balance point is found. On this note, I do want to point out that a 80cm HPM doing 24 damage per 5 sec to shields is basically the same as what a 80cm laser does, except that the laser does 168 damage to shields (at close range) every 35 seconds. Similarly, for mesons I have done some calculations in the past and while of course meson effectiveness depends on the target's shields and armor I can state that for a target with ARMOR_TECH_LEVEL armor thickness (e.g., if the armor tech level is 10, an armor thickness of 10), mesons of similar tech level will have about a 4% chance to penetrate and deal an internal damage hit. So an 80cm meson cannon hitting 8 damage per 5 seconds is dealing an average of 0.32 internal damage per 5 seconds, of course this is not eight 1-damage shots but one 8-damage shot to the variance is very high but the average value is the same, and more importantly I'm not sure this is stronger than what a similar MaxTech laser or particle lance can do although those weapons do need to take the enemy shields down first - though, again, this does vary a lot based on how the opponent has configured their passive defenses.
--- Honestly, while I agree that the tech progression would make Mesons and HPMs an outlier, I disagree with this resulting in an "unsatisfying progression". Nor do I think some techs would be "super-critical" over others. Caliber still scales with Focusing Tech. 12cm over 10cm, and 15cm over 12cm, represent a significant increase in range over their predecessors. Likewise, with the damage model unchanged, more, smaller weapons becomes the only way to generate higher DPS, and at the cost of range, so those weapons remain relevant over a longer period of time as tech advances. Tech breakpoints are valid for three whole tech lines, and require a lot to get to. Likewise, it's not like those gains are retroactively applied to smaller calibers. 10cm is not anymore power efficient at 80cm tech then it was at 10cm.
By "breakpoints" I refer to the fact that every three caliber techs gives a much greater boost to the weapon than the others. With the OP proposal, every caliber tech retains whatever its usual bonus is but the 20cm, 35cm, and 60cm techs gain a massive additional bonus. This is like if we said that the Delta, Sigma, and Omega Shields techs each granted an additional +100% recharge rate (not necessarily in terms of power level but rather as another example of the "breakpoints" I am talking about). It's true that caliber contributes to range, but only to a certain point as once we exceed the BFC maximum range the caliber becomes largely non-critical for range purposes.
That said, I guess what we could do is grade the effective rate of fire (EROF) so it improves with every tech, and the impact is felt on the resulting capacitor requirement. To wit:
- 10cm: EROF = 1.0, power = 3
- 12cm: EROF = 1.25, power = 3.25 (was 4)
- 15cm: EROF = 1.5, power = 4 (was 6)
- 20cm: EROF = 2.0, power = 5 (was 10)
- 25cm: EROF = 2.25, power = 7 (was 16)
- 30cm: EROF = 2.5, power = 9.5 (was 24)
- 35cm: EROF = 3.0, power = 11 (was 32)
- 40cm: EROF = 3.25, power = 12.5 (was 40)
- 50cm: EROF = 3.5, power = 18 (was 64)
- 60cm: EROF = 4.0, power = 24 (was 96)
- 70cm: EROF = 4.5, power = 28 (was 128)
- 80cm: EROF = 5.0, power = 34 (was 168)
This way it is graduated instead of having sharp steps in power level per tech (although the 40 to 50 cm jump looks a bit odd).
The problem I don't see this solving is how to make large-caliber weapons worth using over the smallest caliber that still achieves maximum range, which if I read the OP correctly is something you already are aware of. For example,a 30cm meson caliber confers a 12x range multiplier and is the 30k RP caliber tech. At 30k RP the focusing technology tech gives 60,000 km base range yielding 720,000 km range for the highest-capability meson canon at this tech level. At this tech level the BFC maximum range is 384,000 km, which we could still exceed with a 25cm meson cannon instead (8x multiplier resulting in 480,000 km range). Given this, we have no really good reason to research the 30cm caliber until we develop the 120k RP beam fire control range tech, at which point the maximum BFC range becomes 600,000 km. Even then, we could develop two more levels of focusing tech instead to achieve 640,000 km range, which costs more RP but means we can keep mounting smaller cannons and thus have more effective meson damage per ton.
The proposed change to meson power requirements with calibers does not solve this problem, because (1) we are still mounting bigger weapons that deal the same damage each which means less effective damage per ton, and (2) the power requirement still increases with caliber, so we do not gain anything in terms of DPS from larger weapons. Even with the breakpointed approach in the OP, the only decrease in power requirement with caliber is from 30cm to 35cm, and that is a small decrease that probably doesn't balance out the increased weapon size.
One possibility would be to reduce the range multipliers due to caliber, however this would make mesons and HPMs effectively short-range weapons until mid-to-high tech levels, which I don't think is desirable if the aim is to rework and probably buff the weapons (at least mesons do need some buffs).