I wish there were more options regarding the champions, their rewards, and the response. The champs still need some balance work; this lets players find their own.
Something like:
Champion Easy: you get a champion, no response.
Champion Moderate (number): old way of counterbalancing (offensive increase (5xnum % for waves, 2xnum% for CPAs, num% increase for exos), HW nemeses).
Champion Hard (number): Nemesis response, with 4 being the default (so champ-hard-4 is what is currently happening with them).
Champion Lone Wolf: Boolean modifier to any of the above: just a champion, no minions or modular forts.
Maybe have a nebula difficulty scalar as well.