Is it really necessary to split off, though? It would be the third virtually identical map application in the timespan of a year. Is there no way to co-author? If you suddenly find yourself in need of more time to review your own changes, is someone else going to create another fork, and then another, and one more? These applications are already more or less one-man projects, I don't think losing the coordinated development you have going on now is a good thing.