I noticed that when I pick a map size higher than 1000, say, Ginormous @ 3000 stars, the stars are all clustered. I think I may have fixed it with the following two changes in Ginormous.txt (to pick on Ginormous for the purpose of this discussion):

radius = 500
# original value:
# cluster_radius = 150
cluster_radius = 400 # <-- 80% of radius size (see top line)
# original value:
# cluster_distance_from_core = 200
cluster_distance_from_core = 0 # <-- taken from ncs author

Is anyone else seeing this?