Rather than making the case for App.net in vague generalities, I want to tell you why I made the decision to back the project, as someone who helps run a startup focused on adding value to your existing social networks.

For those that don’t know me, I’m co-founder and head of tech at Goodfilms. Essentially we’re a social network for film lovers, and have built a product around the assumption that the film taste of the people in your existing social networks is the biggest predictor of your interest in films. We then integrate that with online film services like iTunes and Netflix, to make it easier for you to watch the films you find out about from your friends.

We’re trying to be the central “glue” in your online film life — helping you and your friends find the best movies to watch online. So you can understand that we rely on integrating with third parties operating in good faith.

It’s a classic host-beneficiary relationship with each service we’re connected too. We take value out of the third parties we integrate with, either in information from the users’ social graph, or information on which films can be rented where and for how much. We provide value by driving greater engagement with their products and offerings.

That’s the theory. In practice, there’s really nothing in place to keep the goals of both parties in alignment. Twitter, Facebook, Netflix, and so on are all building their product and have their own goals to achieve, and so do we. If we needed to do something to our product that wasn’t aligned with their goals, I would make the change without too much thought. So when a company opens an API and says “let a thousand flowers bloom”, I’m happy to take advantage of it, but am not so naive to think that our goals will always be in alignment.

What I am, with regards to third party APIs, is weary.

Take this week’s announcement from Twitter regarding their API. I don’t want to jump too hard on the “how dare they” angle, as it’s their business to run the company and do what they like. We are not their customers, and if they need to sacrifice large segments of their app ecosystem (whether that is true or not is for someone else to argue) to do the right thing for their customers, then that’s the way it has to be.

The problem, for me, is that keeping up with all these changes takes time and effort. Your product starts marching to the beat of their drummer. When you multiply that effect by integrating multiple services, keeping a steady rhythm is difficult. Every hour I put into learning the ins and out of each system’s terms of service is an hour I’m not putting into learning the needs of our users. It’s important for me to know the terms, not just for the strict mechanics of “can I do X with this service”, but also “is it wise to couple our business to theirs”. Their launch dates become your launch dates. Every line of code in your application is a liability, and every line that you have to add to support their goals rather than your own adds up.

This is what excited me about App.net: it offers to be, for users as well as third party developers, the same social connective tissue as Twitter or Facebook – but for a fee. The fee simplifies the value proposition. It will be a social graph you can rely on to be simple and predictable, and you will pay some money for that. Or not, if that’s not something you value.

When I clicked the “pay now” button, I had, and still have no idea if the product would actually work. I’m still a little unclear on exactly what the product will be, but I’m happy to spend $50 on a punt to find out. I’ve spent more on web and desktop apps to make my life easier, so why not pay to make my life online easier?

If it does become the social network Dalton Caldwell has promised, it sounds like $50 well spent. If it fails, there is still value in being part of a collective sending a half a million dollar message to Twitter and Facebook saying that we’re happy with a boring, predictable value proposition: you provide value, we give you cash.

The real reason I signed up so early: the username land grab. With a common name like John, the only way I’m going to get my first name is by greasing the wheels with a little green.