my OoA Assassin was sitting at 18k or 19k damage if i remember correctly, while my nec was at 15k. Didn't try as hard on my nec though. The doom curse makes a huge difference in damage, made killing all bosses until 125 a breeze.
I got my ssin to around 49k mana, which let me cast 5 OoAs in a row but every further OoA took around 2-3 seconds of mana regeneration, which felt quite slow. The mana sweep proc from witchmoon made it tolerable in packed places like fauztinville
should be weaker in current patch though, since they lowered OoAs base damage in 1.3
I would really like to see an OoA ssin and necro team up. Doom + manatide totem for both. I am wondering how far they could go in labs