Well part of the good thing about open source is that you allow other people to have access to the source so that they can apply patches and make it better, A lot like what Rojo has been doing. If you close source the exporter people wont be able to do that.
Im not against going closed source but I think that you might be taking away valuable resources. There may be some way to open up the source for outside development and then they have the option to apply the patch for review. I think that would be an awesome way to go about it.
So it would be kinda like you have a Dev pay option where you get the source code for the exporter that way you can change it and then they have the option to submit a patch for review and possible addition.