Well it sounds like your implementing a feature that is slated for the 1.9 release... user accounts. I believe that this feature is already being worked on by the devs.
Pro: You will have user accounts prior to everyone else
Con: You are probably removing the ability to easily upgrade to new versions (like 1.8 which is currently in DPR, and we should start seeing release candidates soon)
You could submit your code changes on github and the devs may use it, but like I said I'm pretty sure that since this has been in the pipeline for a while that they have been working on it already and your changes may not match what they have chosen to do.
This thread seems better suited for general discussion since this is neither a suggestion nor feedback. I'll move it for you.