I haven't thought about wracks yet.. I may convert this model.
I want a admech/SoB/DE vibe. My back story is here
http://ngc40k.proboards.com/thread/73/first-draft
I want the characters to evolve but I plan on running to the dark city to escape imperial persecution. Fight in the arena and rise like spartacus. Only to fall of course.
What did you do for your wracks?