These It's undeniably a horrible thing also let down by it's substandard screen resolution,contrast and brightness - 3 things which effect the quality of mapping and navigation. You may also notice that any input makes the unit freeze for a year before loading it's next screen.
Maps are OSM - which evidently means that many roads don't exist.
I may need to be corrected but the Bryton is also tied to their own site for planning and downloading routes.
IIRC: To share with strava you have to upload to bryton - download the GPX and upload it manually.
Edge800 will happily upload and download directly to/from anywhere, inc to the unit itself or the SD card. ie: You can tell strava that your log files are on /sd or Garmin Unit:###343#3 blah blah
By most accounts the edge800 is an unfair comparison. The Rider50 if at all, is a rival to the 705.