I agree with everything you wrote except I think the starting companions of a bound hobgoblin and imp is cool. I'd like to add that the perhaps adding special invaders, like thieves who can bypass traps, paladins resistant to lust, sorcerers who conjure an antagonist to fight for and before them, and I am sure we can think of many more varieties to spice things up in the later stages.I also think the invaders should avail themselves of whatever the room they are in has when they win combat -- healing & bandages in infirmary, food in farm, gold in gold mines, etc. just like they do in the stockroom. Right now I am running 3 thematic dungeons: en elven, a koboldian, and a cyclopean dungeon. Each built around a theme and very different from each other. With the addition of more types of rooms more thematic dungeons can be devised.