I said in another thread somewhere that it would be nice if one could select multiple objects in the population.
Say 3 different objects for example and have these type of settings that could be changed to whatever you need:
Object 1 = 70% coverage
Object 2 = 30% coverage
Object 3 = 5% coverage
Would also be nice with a "clumping" option to have control of how much they should clump together.