I do understand your point but I am afraid out of all the applications mine is the one that we won't be able to integrate to the others. I believe all the other applications (even the ones using google data) render their own maps. Geeps uses a web browser (webkit) and leaves all the rendering to "google".
You also need to keep in mind that they are not all developed using the same language and may have different goals. Like you I would like to just have ONE gps application that really works with all included (offline, voice directions, good local business search, integration with other apps, poi....) but haven't found it yet.