I have a missile boat design that I've been continually making minor updates to. The most recent tweak was to swap out its gamma shields for deltas. That's it. That's all I did to it aside from redesignate it from a fast attack craft to a missile boat.
I was even able to refit this thing from ion to fusion drive at a 75% and change fee without issue.
Skadi IIb class Attack Craft 2,400 tons 257 Crew 483.1 BP TCS 48 TH 56 EM 120
3333 km/s Armour 2-15 Shields 4-300 Sensors 6/6/0/0 Damage Control Rating 1 PPV 12
Maint Life 3.41 Years MSP 126 AFR 46% IFR 0.6% 1YR 17 5YR 248 Max Repair 80 MSP
Magazine 104
GB Magneto-plasma Drive E80 (1) Power 160 Fuel Use 800% Signature 56 Armour 0 Exp 15%
Fuel Capacity 100,000 Litres Range 9.4 billion km (32 days at full power)
Gamma R300/16 Shields (2) Total Fuel Cost 32 Litres per day
Size 2 Missile Launcher (6) Missile Size 2 Rate of Fire 20
Missile Fire Control FC57-R100 (2) Range 57.6m km Resolution 100
LOM2 Shuriken (51) Speed: 20,000 km/s End: 37.5m Range: 45m km WH: 4 Size: 2 TH: 66 / 40 / 20
Active Search Sensor MR2-R1 (1) GPS 48 Range 2.9m km Resolution 1
Active Search Sensor MR50-R110 (1) GPS 8800 Range 50.3m km Resolution 110
Thermal Sensor TH1-6 (1) Sensitivity 6 Detect Sig Strength 1000: 6m km
EM Detection Sensor EM1-6 (1) Sensitivity 6 Detect Sig Strength 1000: 6m km
Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s
This design is classed as a Military Vessel for maintenance purposes
The new version:
Skadi IIc class Attack Craft 2,400 tons 257 Crew 485.1 BP TCS 48 TH 56 EM 150
3333 km/s Armour 2-15 Shields 5-375 Sensors 6/6/0/0 Damage Control Rating 1 PPV 12
Maint Life 3.4 Years MSP 126 AFR 46% IFR 0.6% 1YR 17 5YR 248 Max Repair 80 MSP
Magazine 104
GB Magneto-plasma Drive E80 (1) Power 160 Fuel Use 800% Signature 56 Armour 0 Exp 15%
Fuel Capacity 100,000 Litres Range 9.4 billion km (32 days at full power)
Delta R375/20 Shields (2) Total Fuel Cost 40 Litres per day
Size 2 Missile Launcher (6) Missile Size 2 Rate of Fire 20
Missile Fire Control FC57-R100 (2) Range 57.6m km Resolution 100
LOM2 Shuriken (51) Speed: 20,000 km/s End: 37.5m Range: 45m km WH: 4 Size: 2 TH: 66 / 40 / 20
Active Search Sensor MR2-R1 (1) GPS 48 Range 2.9m km Resolution 1
Active Search Sensor MR50-R110 (1) GPS 8800 Range 50.3m km Resolution 110
Thermal Sensor TH1-6 (1) Sensitivity 6 Detect Sig Strength 1000: 6m km
EM Detection Sensor EM1-6 (1) Sensitivity 6 Detect Sig Strength 1000: 6m km
Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s
This design is classed as a Military Vessel for maintenance purposes
I tried changing the designation back to attack craft from missile boat to see if it would help but no dice. When the new shields became available, I immediately created variants for all of my shield equipped ships to take advantage of the new technology and none of them had any issues.