What a coincidence. I ate precisely six planets, completely, plus a great many asteroids to complete this ship (Shiva - Destroyer of Worlds).
I'm not sure I'd call it a 'moderate' size of ship however. It is well over two million blocks.
I ate six planets, used what I could of those materials, sold the rest denuding two systems worth of shops of both cash and essential components such as shield, jump and armor, then a visit to spawn to shamelessly exploit it's reserve as well. It took at least two full days of effort just for the materials alone, not to mention the several days spent in construction.
Germane to the subject of this thread, it takes 320K thrusters to give this thing a thrust response I consider barely adequate (burning 12 million power). 185K jump modules give this a jump recharge rate of 18 seconds, which is about as slow as I can live with in a ship I will be piloting a lot.
I should also mention that the only reason I am flying this as opposed to a battle cube is because my server admin turned the TURNING_DIMENSION_SCALE = 1.1 in the server.cfg file down to 0.8. I consider sluggish turn rates SO debilitating, that if we did not have this option, I would either fly small battle cubes only or simply not play. I keep holding out hope that some option will someday exist to devote extra mass/energy in a ship to improving turn rates.