So, MagicFab, lemme get this straight.
You went from a commercial offering (me too: I was using Freshbooks) to Invoice Ninja because it’s code is open source and you can self host for free. By the way, I love that by having access to the source code I can customize it to my business’ needs.
Hillel (always helpful) and other developers, just like us, have bills to pay, so they have to find ways to monetize Invoice Ninja. Yet they are still willing to provide the full source code for anyone who wants to do a bit of work to host their own instance.
Their monetization is based on providing a ready-to-use version (hosting/SaaS) and a mobile app, which is either free (if you subscribe to the SaaS version) or with a small in-app purchase (if you self host). The subscription costs $6,66 or $10 per month, and the in-app purchase probably costs even less. Even the white label license is incredibly cheap ($1,66 per month). I was paying Freshbooks $29,95 per month and it didn’t have all the possibilities that Invoice Ninja provides, even with their flashy brand-new version (I was really disappointed when they told me about its features).
All in all, I assume you run a business and uses Invoice Ninja to track your customers, invoices and payments. And you’re telling us that you really, REALLY want everything for free?
“The main reason I moved to Invoice Ninja (as a paid customer from the start) was to avoid any of the proprietary offerings out there.”
“I’d really like InvoiceNinja remaining coherent with its initial licensing model”
I mean, c’mon, really? You know these guys really have no obligation to license ALL of their work as GPL, right? In fact, they even have no obligation to provide the source code, they could simply provide the SaaS offering and that would be it.
I may not fully understand your point of view with your question, but I believe that the open source movement is about collaborating and contributing, and so if you’re so inclined in having Invoice Ninja on the F-Droid market, why don’t you start by creating a simple web wrapper? Invoice Ninja has a nice responsive interface. I have a Windows Phone device and so there’s no app but I can still use it nicely via the browser. And it’s way better than that 90’s-inspired Freshbooks interface.