I think you can do more with a ghost ark e.g fill it with models and get them to shoot out the top, transport, and replenish warriors, whereas the doom ark you just have to sit it in a good position and shoot it. You can magnetise it because I have seen a couple of people do it on youtube, but you will need a lot of magnets.
I still want to try out moving 10 immortals in the ghost ark surrounded by a 20 man squad of warriors with a d lord and see what they can do, thats a heck of a lot of shots.
Me: To be honest im amazed there isn't a chaos god of not revising or at least chaos god of procrastination
MidnightSun: There will be, when enough people do it. Y'know when the Eldar were all engaging in their hedonism and Slaanesh ripped open the Eye of Terror with his creation? Slaanesh will have NOTHING on the God of Procrastination, and his vile minions will carve the galaxy asunder in a thousand year reign of blood.... Tomorrow