Actually, I would like an external GPX logger that can record GPS, GLONASS, Galileo and Baidu in separate files and as vectored filtered track (5 files in total) with HDOP in the recorded tracks. That would enable filtering to remove low accuracy segments, selecting the system with highest accuracy, or using combined track, depending on conditions. Operating in tropical environment where atmospheric disturbance is affecting position accuracy during certain times of day (typically just after sunrise, just before sunset, and at solar midday).
Currently I work with scripts for processing combining GPX tracks from my two VIRB units and a Nüvi unit, and at times logs from myTracks on my phone, using gpsbabel to combine them