I use a couple of house rules, mostly to change the flow of the game and campaign to one that suits myself and others.
Firstly I drop the compulsory close at the start of the round. This give a downed model a little time to survive and isn't auto killed unless a player decides to use their turn to do so. Adds a risk management to deciding who you want to activate.
In PvP games we up a Threshold Agent to Dex 4+. Like you've mentioned, they can get overwhelmed against a horde of cultists who are shooting with the same ability to hit. I don't do this for the solo cards though. The models can act randomly on some occasions, so it's not really needed.
Lastly I add +1 to the result for rolling for a Map Pieces for every previous game I've played in a campaign. I once played 9 games and got no pieces, so this allows us to get the more interesting scenarios on the table quicker