Once you rank up, the NX class becomes practically useless. It really makes buying the bundle/ship a waste. I was very excited last time I received payment to buy it, but was disappointed when I learned of how weak it was (I am level 50).
I believe that all C point paid ships that are bought at lower levels, should scale with player level, and become equal with the ship level of the player. This would include weapon slots, hull plating, and pretty much anything such as turn rate and abilities. For example, the NX class would scale with escorts, and the Constitution would scale with Cruisers. I think this would be fair to justify the prices of the ships.