It's looking like the shields off the ships are ship specific, at least in 2.3.1.
I can swap the Invincible and Invincible Quad between the hornets, but not onto the Avenger Titan (which has a s3 port) or the Freelancer (which has a s3 port). Nor could I put the Freelancer s2 shield onto the hornets, although the SH port says it accepts s2-4. (Interesting trivia, the Freelancer shield s2 shield is better than the SH s3 shield).
Further the Invincible X will not fit on the Hornets nor the Quad or base Invincible on the Cutlass.
The Ink-Mark 304 (s3) *did* fit on the Titan (2.1-2.2, I've been renting it for months). It no longer does. In fact the rented components do not fit on *any* ship I have access to (I do not have a Gladius, Scout, Gladiator or Sabre to test).
The LN, like the 325, has 3 s1 shield ports. The Delta has a single s1 shield port. All three have armor.
At this point I can not recommend mucking about with shields, and I do not think either power plants or coolers make a difference, yet. They *will*, but they don't yet.
I will post as soon as something changes.