Still not convinced about that weaponry, not just the FC aspects.
Using 4x4 Meson Cannons 'mostly for point defence' is suspect when Railguns are so efficient on a moderately fast ship. Little or no additional research is required, and volume of fire instead of high tracking speed means we don't need sophisticated fire controls to be effective.
4x4 Meson Cannons make more sense as general purpose weapons - only mediocre point defence, but reliable damage dealers. But that's tricky too, as then we need to consider synergy with our long-ranged weapons.
If someone crosses into Meson Range, our firepower is split between medium-sized lasers that'll scratch the paint badly but can't be expected to burn through defences in a single shot, and peashooters that ignore defences.
This is wasteful. Equal-sized laser turrets would take better advantage of existing armour damage, and have considerably longer range so we could slave them to the long-range fire control for enhanced capabilities at range. Since unturreted and turreted guns are only one size apart and the larger cannons have the same RoF with your capacitor tech, unifying everything including fire control would be better still.
Getting truly long range with Mesons is expensive and we don't gain damage potential in the bargain. Fitting lasers to a primarily-Meson ship for cheap shots is fine in principle, but I struggle to find an implementation that wouldn't be better as something else.
I see the main appeal of Mesons mainly for things other than mainline combat vessels: fighters, fast snipers (especially against certain spoilers), support for boarding actions, PDCs where other beam weapons would be ineffective...
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Whether the MSP situation is a problem depends on many details... as it is, it seems a serious limitation but not an unreasonable one given the intended use.
