It's the equivalent to the scroll speed in mania. I don't see the problem.
Italo wrote:If I had stars I would shoot them, totally support but I don't think that people will aprove this since that can make the gameplay more easy in some cases.
If you put "ApproachCircleStartingSize: 4" on a high AR map, for instance, the approach circle would be huge and speeding inwards. On a low approach rate, it would be going inward slower.