Well, if you use a lower gamma it's gonna make the circles disappear faster than normal.
on the other hand, higher gamma makes the circles "take longer to fade out"
With that in mind, we can conclude that: High gamma - better for HD mod and possibly high ar
Low gamma - better for EZ MOD and low ar
High gamma - more objects per time which helps read some higher ar.
Low gamma - the opposite, less objects per time which helps read some lower ar bc there are a lot of objects poppin in.