Let me say, I absolutely love Eldritch Horror and all the changes it made. I honestly can't think of any major changes I'd make for an expansion (other than adding more cards).
But...up until now I've been playing only 2 player games. Recently I've tried some with 8 and it seems way too easy. I don't think the challenge scales enough as you add more people.
I'm not talking "easier in some ways, harder in others" like in Arkham Horror (where more investigators meant easier to win by closing gates, harder to win final battle), I'm talking easy period.
Comparing 8 players against 2:
-4 times the number of investigators
-4 times the clue requirements, but 4 times the clue spawns to even out
-Only 2 times the gate spawns (with no reduced max gates as you add more players mechanic like Arkham)
-Only 3 times the monster surge (which almost never comes into play because it's easy to keep the gates constantly shut with 8 players and only double the gates)
-Epic monsters barely get tougher as the player number goes up. Only +1 health per investigator. Getting to and killing an epic monster (helloooo, spinner of webs!) with 4 health in a two player game is much tougher than sparing the manpower to kill a 10 health monster with the same stats in an 8 player game.
Not to mention the fact that since so many investigator abilities and spells are global (politician, psychic, actress, flesh ward, instill bravery, plumb the void, etc.) compared to Arkham's mostly personal effects, you get more exponential benefits as the investigator count climbs.
2 player games you can't really afford to go out of your way to close many gates, and it's a race to solve the mysteries as the gates get out of control. My 8 player games so far it's not unusual to have zero gates open at any time, with the max being one or two. The doom hardly budges. It seems the only possible way to ever lose with 8 is for the mythos deck to run out, but I don't see that happening due to all the crazy global combos possible with a lot of investigators.
Basically it seems like with more investigators, the challenge increases (at most) arithmetically (only when it comes to clues, gates and monsters are easier) while the player strength increases geometrically. I don't want to make any major changes to the game, but I think the difficulty increase for more players needs to be looked at. It might even be as simple as increasing the gate spawns and monster surges (3 gate spawn for 7-8 players, 4 monster surge).
What's everyone else's experience with small vs large games?