I agree, SpectralMeat, it's lame that the actual important stats for shields don't show up.
You can definitely tell a difference when you swap them out. I had a class 5E shield and that sucker only went down when three people were shooting me. I changed to a 3C and it goes down with 3-4 laser shots now.
If you're going to be fighting, you want the highest class shield you can get. If you are space trucking, you can cheat it down a level or two to get more storage space. Some people outright sell their shields...but I'm nowhere near that brave.