The ability of gform_after_submission works for posting to third party marketing automation systems, but it can actually cripple a lot of functionality. For instance, we use Marketo. Onsite forms that submit to Marketo capture a lot of other information beyond what the form does.
I'm not interested in using Gravity forms for storing our data, but purely for form creation. I need to be able to alter the actual form action.
How can I do this?
The only way to alter how Gravity Forms runs is through our hooks and filters, and you've already found the hook that we have to do what you are looking to do. Gravity Forms wasn't built to just create forms, but also to capture that data. and as such we haven't developed it in a way that can be used just as a form builder without capturing submitted information.
You could always build the form in Gravity Forms and use the gform_form_tag to change where the collected data is sent: http://www.gravityhelp.com/documentation/page/Gform_form_tag
