I did some analysis on integrating Marketo with AEM. It appears that Marketo does provide some API for the Leads submission. There are instructions on Developers.marketo.com
I think this would be the appropriate one for something like a Contact Us form where email/first name/ last name are captured.
But to access those API, we need to establish a “handshake” with Marketo using OAuth, so a Oauth provider needs to be created at the Marketo side and at AEM side a OAuth consumer needs to be created. Once the “handshake” between AEM and Marketo is establish we use their API.
Huge DoS vulnerability, here we come! This is not the way it should be done in a professional environment.
(Also, they don't really understand how the API works. You wouldn't be creating an OAuth provider in Marketo, just an API user, which is not the same thing. But they don't need the API anyway.)
This blog post outlines the recommended way to use Forms 2.0 API to perform a background form post to Marketo. It can be used with any CMS, any form, and gives you scalability and stability.
Thank you for the quick response! I'll show my web team the link ASAP and hopefully we can use that and not the consultant's idea.
As always, you are an awesome resource, thank you for your help!