This sounds amazing! I've only tried up to normal difficulty but really like the mode. I often play with a Tone as i like the Sonar ability and Monarch to hand out healing. (Plus using the scope ability with an fully upgraded XO-16 means you can blast those critical red area's on a Titan) Some teams seem to simply gel and everyone knows what needs doing whereas others I've played on quickly lose the Harvester in no time at all. More maps would be nice too..
It's cool, would be mean if it was 4 vs 4 kind of like how Bounty is, but then I suppose that would defeat the purpose. The AI grunts could be a bit more clever though, like in Attrition they are just there to die. Would be mean if they were like the Reapers, a real challenge. Awesome to have it in TF2 though, good fun.
Mind you, I do have to stop trying to go fist to fist with the Reapers, I never seem to win that one!!! hard case though.