At first level game feels a bit easy for me and have too many explosives. But at next levels i recall statement "Ammo can be only low or low but can't carry more".
Regular mobs feel no so problematic for me even at maxed, but last boss can be. (At dominator I kill almost(except end boss smash me hmm ~8 times, and E3 kill me two times) bosses from two tries, and feels like MAXED gives +30%, I don't try to non-cheat kill on MAXED for now)
Upd 1: I already (on first test) finished first level on MAXED with wrench only...
Upd 2: Sometimes I can be slightly hardcore and ammo-preserving-slow-kill-and-broke-everything-player so my impression from difficulty can be not so average...