Because mass will affect ALL things your ship does, from your jump distances to your maneuvering capabilities and speed, I would think that adding a shield like that to anything short of a tank oriented Anaconda would be a bad idea.
Unless mass only affects jump distances, in which case GET ON THAT FRONTIER!
That thing is a beast. Possibly the letters are a placeholder system, or maybe we're going to get some more information on what they mean eventually. I say you do some research, then buy it and study the difference!