With all the different variables and permertations of the different inserts, vanes, and broadheads available, it's all about balance. The laws of physics states that no matter what you do, you'll always end up "robbing Peter to pay Paul". So if you can find the combination with more pros than cons and that work best with your setup, you'll be all set.
Now to answer your question, in a nutshell, yes lighter inserts and heavier broadheads do work.