Integrate with newer versions of Quick Books
It seems to me that you should either start integrating with newer versions of QBs or just eliminate the QB export entirely. I say this because who is still using the versions of QBs you support? Those versions are so old not only are they antiquated and just generally out of date they are no longer being supported by Quick Books and the only solution you have if you encounter an issue with those versions is to update to a newer version that is supported. Also it seems like you have to the frame work in place to do this it just needs to be updated. Honestly if there is anything that makes me switch over to other platforms it will be for this reason. Also don't take the half-assed approach and integrate with QB Online because everyone hates that version.