I don't know the Dynamics connector, but for what it's worth:

You can always access the form fields in events belonging to the EPiServer.Forms.Core.Events.FormsEvents-class, so you have full control over everything that comes in from the client (in the expected FormsSubmitting and FormsSubmitted fashion); reading or modifying values of every form field as you please.

So if the marketing connector has some API you can use, this could at least provide some opportunities. If it doesn't already integrate out of the box with the forms, that is. Which I doubt, since Forms is a fairly new module.

The marketing connector is an EpiServer product that specifically made for connecting forms, personalisation groups and a few other things through to your CRM of choice without having to code it up. This product doesn't have an API and it directly intergrates into EpiServer. My question was more around the fact that I know EpiServer said at their last meet that they had a team working on stories for updating it from XForms to the new Forms system. I just wasn't sure on the status of said upgrade

This is currently being worked on and nearing completion. I expect the development work to be done in the next week or so, then QA will take a week or two, so we should have a release by the end of April.

Awesome thanks R Sterry, very helpful