I have also seen it. Yesterday, in the game I am playing, I saw a stack of 27, then I saw this stack of 76.

I would have a lot of problems with these in a fleet since I have no missile defense, and they have armor to defeat my projectile weapons. Our logistics are the same, so our fleets would be unevenly matched, with me on the loosing side. My fleets against a single ship of theirs would give me a good chance of winning each battle. It would take a long time and be boring, but I would eventually win enough to offset my loses.