How do I change the price of a flat rate shipping fee depending on a type of Product?
figured it out .. but not sure if its the best way i think it is. for reference:


created a light &amp; heavy shipping flat rate option.
added in new conditions matching if its a heavy or light via taxonomy terms.
added in an extra condition for LIGHT shipping to make it disappear by detecting if there is a heavy item in the cart by doing a negate on the same above condition.


To make this work you will need https://drupal.org/project/commerce_rules_extra 

As you need the Total quantity of selected product comparison condition to loop through the entire cart and match what you need in accordance to the terms you select.