As suggested above the issue is what else do you compromise, and how do you cope with those compromises.
As much as I love my Couriers, I've recently begin to notice that for certain roles a Mamba or Krait Phantom can be an easier choice. For example I've got a
598m/s Mamba for CZs that is as quick and with much more firepower than most Couriers... but not all. For example
Turn n Burn is much faster, has a reduced fuel tank, and an overcharged powerplant that is so hot that you need two beams on Thermal vent to keep it cool. But they do keep it very cool....
However to answer your original question, you have two choices with Prismatics, make them so strong that you can tank the incoming fire, or make them efficient to better fit the Courier. Your problem is likely to be how much you compromise the rest of your build.
For tanking, if you are struggling for extra power then Thermal Resist doesn't add to your power usage, but Reinforced will give you protection from everything that gets thrown at you, maybe
something like this.
If you are really struggling for power and/or weight then you want to engineer with Enhanced Low power, which improves everything a little, don't bother with a Class 3, there is little difference to a Class 2 for a lot more weight. For example this has
more firepower.
For shield boosters, I don't think you ever want a 0A on a courier, they are just too heavy. Engineer some 0E/0Ds. You want one as a Heavy duty to give you a massive boost, then up your resistances for the others, usually one as a Thermal resist, the others as Resistance augmented.
Finally, if you can afford it, I would buy at least 2x Class 2 and 2x Class 3 Prismatics on Thursday. That way you can try out all your options until you find what works for you.