I personally view the difficulty above .5 the next star.
Above 2.5 = 3
Above 3.5 = 4
Above 4.5 = 5.
Regardless of what it actually is i notice a bigger difference in overall difficulty between say 3star and 3.5 star rather than 3.5 to 4.
But that's just me. I know once you reach 4 - 5 maps some seem like they deserve a 6 star rating while some seem like they deserve a 3 star rating.
Above 2.5 = 3
Above 3.5 = 4
Above 4.5 = 5.
Regardless of what it actually is i notice a bigger difference in overall difficulty between say 3star and 3.5 star rather than 3.5 to 4.
But that's just me. I know once you reach 4 - 5 maps some seem like they deserve a 6 star rating while some seem like they deserve a 3 star rating.