Regardless of the brush size, entities are only being removed in one chunk. This picture shows what I mean: https://www.dropbox.com/s/b4fo29gud8js8h0/2014-04-13_18.32.29.png

For safety reasons we changed that Brush to use a rounded system, where the size is rounded to chunks. So brush size 16+ would then allow you to do more than 1 chunk.