This is an interesting question. It's hard to know the right answer for you without more details about your product, however I'm inclined to say you shouldn't open source your project. I only say this because the reasons you want to open source your app aren't realistic:
I like the idea of open source collaboration and making our code for our application we are building public on github.
Unfortunately most open source projects live or die based on the work of the founding team (whether it's one person or many). In other words, the biggest contributions you'll get is small bugfixes and maybe minor functionality additions. No one will help build your business for you.
Reason to open source your app
If you can split your product into separate components you could open source bits of your app to great success. Without knowing the specifics of your app I can't tell you how you should split your app. Instead I'll explain how we open sourced about 2/3 of our product and attracted large customers because of it:
At our company we take a hybrid approach for our updater suite, wyBuild. There are 3 parts to the app:
- wyBuild: design and build the updates [closed source]
- wyUpdate: the actual updater program that our customers include with their app [open source, BSD]
- The AutomaticUpdater: an optional component that our customers can include with their app that automates the entire update process [open source, LGPL]
Because the "parts that did the updating" were completely open source we have been able to get large orders from Fortune 500 companies. Invariably the reason these companies end up purchasing wyBuild is that the CTOs first encountered the source code. I sincerely doubt we could have attracted some of these larger clients if our product was completely closed source. At least not without a couple of million dollars more in our advertising budget.
To open source or not to open source...
It depends on what type of app your making. There are valid (and profitable) business cases for open sourcing your app; our story is a single anecdote, but there are similar cases at both small and large companies.