I have several forms on the website, and the only ones which currently are not working are part of the gravity forms for woocommerce add-on. The regular gravity forms are working fine.
I have several products which utilize gravity forms for selecting multiple options:
http://thechocolateswirl.com/shop/bp/brownie-pop-custom-assortment/
http://thechocolateswirl.com/shop/truffle/truffle-custom-assortment/
These forms should update flavor fields when you select a larger size (see the forms for explanation).
I am currently using gravity forms 1.6.12 and woocommerce 1.6.6 (I am waiting for several of the new bugs to be worked out of woocommerce prior to updating to the newest version 2.0.4). Please let me know if there is anything else you need. Thanks! :-)