Hey there, I'm diving very deep into Mautic, which is the only Open Source Marketing Automation solution available in the industry right now (to my knowledge) and it is an extremely powerful platform, with numerous top SaaS API integrations already available.
I would like to suggest that you make Hustle work as a direct API integration with Mautic, as Thrive Leads has already accomplished this, but I feel that Hustle should be a no-brainer option in Mautic Plugins.
Please look into it, as Mautic is intending to position themselves (and they're well on their way) the "WordPress" of Marketing Automation
Just a thought...
West County Media
EDIT: I was just informed by Live Chat support that this is already done, since version 2.1.4 released Aug 9 so great job guys, sorry for missing that one..!