I have to admit, I never found them to be very useful in game. I preferred their orb-powered equivalents that also came with enough boarding troops to actually not die to a frigate in melee.
Maybe not needing to paint sails also influenced my blatant favouritism here. The last ones, heavy cruisers, were the ultimate release for the Thaniras Elves before the system faded away. The fact that I did not even bother to paint them shows that they already came too late.
Next time, there might be dragons.