Also, how does shock damage (which is supposed to be the great equalizer here in many respects, if I recall correctly) factor into the efficiency vs. redundancy conversation? Obviously, the more shields a ship can carry the less it fears shock damage, but I do not a lot of players (myself included) prefer to go skimpy on shields and rely on armor for protection for sheer tonnage efficiency anyways.
That might be a mistake with larger ships, with the threshold of "mistake" something we could probably chart on a graph comparing shield generator efficiency against armor efficiency...
It is very difficult to calculate the value of shields as there are no mathematical way to know how important protection against chock and the regeneration effect of shields will impact the overall efficiency.
The only thing I know is that shields is a very powerful tool in most real practical situations that I have used them. I usually see them as a force multiplier in terms of defensive power. Shields obviously have less hit points than the total armour points on a ship on a ton for ton comparison. If shields did not have that they would be seriously over powered.
I honestly wonder if shields are possibly too strong after the early to mid tech levels, since they do not scale linearly, but given that for armor a practical rule of thumb is that it takes eroding ~50% of a ship's armor before internal damage becomes frequent and catastrophic - a very approximate rule, but sensible in general - if shields are even "only" 50% as size-efficient as armor at typical tech levels this would make them in practice just as good, and then better because of the additional advantages of shields (ignore weapon damage profiles, recharge vs repair, corbomite vs duranium to build, etc.). I would guess that probably to be reasonably balanced one would expect shields to be roughly ~33% as efficient as armor per ton, somewhere in that 25-40% range is probably reasonable.
For example the following Epsilon-level (15k RP) shield:
Shield Strength 119
Recharge Rate 75 Recharge Time 476
Cost 194 Crew 25 HTK 5
Size 25 HS (1,250 tons)Development Cost 984 RP
Materials Required
Corbomite 194has an efficiency of 4.76 points per HS, which compares to roughly Laminate Composite Armour (20k RP) which has 12 points per HS, so the shield is just under 40% as efficient as armor at the same tech level, which is pushing the upper bounds of "balanced". The efficiency can only get better since shield strength scales with generator size to the (3/2) power, and size maxes out at 50 so the tonnage efficiency of shields will eventually exceed 50% that of armor. So probably around the point where you start talking six digits for tech costs I'd be willing to bet that shields become basically superior in nearly all cases, at least for military ships.
This is probably a bit exacerbated by the fact that there is no real anti-shield weapon in the game. The bonus damage HPMs have is not really that much in raw damage per increment, and while railguns are fairly effective against shields compared to lasers, lances, etc. this is not saying a lot as the latter weapons are just countered strongly by shields.
...
Also, as an aside: when speaking of
shock damage it may be useful to note that a
chock is something rather different.