2x EXP and DROP Event - August 4 and 5

It becomes more difficult because the mobs would be 170 and pack much more of a punch.

Normal Mode in the 160+ area is equivalent to Hard mode in 120-159. The Normal 170 mobs have slightly less HP than the Hard 140, but the 170 mobs have higher exp. If you are doing it in Solo mode and don't like the low spawn, just make a party of 1 and go with Party Mode. That's how I grind.