Sure, give it a try if it fits your case. Bear in mind that reitti is really designed to track your whole day and only your personal movement. It will happily create a visit if you upload two separate gpx file with a gap between them of a day or so. This is a feature to circumvent battery saving modes and missed tracking in the accompanying gps apps.
It can work but it sounds like you would benefit from the devices feature in the next release (not counting bugfixes here) The plan would be to merge then all gps data (automatically or manual) into one timeline. So all data of all devices together can be your personal movement.
That would be awesome. If something needs to be done, I could probably incorporate that into the device’s support. It is currently in the planning phase and still open to suggestions and ideas.