Just a general comment, and one that I want to bring @rmandelb into.

Do we have sufficient regression tests to ensure that when we make changes like this to the way that the magic numbers are used that we are still getting what we expect?  I know that there are tests against saved images in the unit tests, but some of this behaviour is dependent on crossing certain thresholds.  Now that we have a way to make these numbers more easily user-changeable (e.g. on #343), and therefore change-able from within tests, we should probably try to include regression tests that properly explore what happens when one or more of these numbers are actually invoked.