Both Garmin and Bryton are dedicated cycling GPS. The Garmin Edge series (except the 200) is more expensive because it also incorporates the barometric calculation of elevation or altimeter. If you notice hiking GPS like the eTrex10 or eTrex 20 the elevation calculation requires at least 3 satellite fixes to formulate the algorithms for the elevation of your location. Even that , the calculation is not accurate compared to those having the barometric sensors. Only the more expensive hiking GPS have this function and all Edge series have this. The elevation measurement is on my regular data window apart from speed, distance and time. Off course others includes the cadence and HRM readings.
Sometimes, when we cycle, the strokes seems hard and the terrain looks flat and we can confirm it is actually a slope by looking at the elevation readings. Initially when we read , it was eg. 70m asl and then after a few strokes it becomes 71m and later 72m , then we know it is a slope or vice versa when we feel the strokes are easier. I didn't read the literature of the new Brytons on whether they are using barometric sensors or not.
When my wife was using the Bryton 20+ , I compared once when the map of the activity is downloaded and I was also surprised that the Bryton is more accurate if not better than the Garmin Edge. I am sure the latest Bryton won't disappoint users after all, their initial models are all now replaced with better models and they have actually learn from the feed backs of the users.
Also the size of the unit is also a factor and they need to minimize to suitable size for cyclists. For this, a whole new circuit design is needed and the market for cycling GPS is not as big as their regular GPSes. Hence the high price which is made even worse with our depreciating Ringgit. Then again if you look carefully, it is also the need of the users. If they need it, it is worthy. A Sigma or a Cateye cylo computer with Ant+ functions for HRM and cadence is not cheap either and I rather go to the specialist even though I pay slightly more. So, either Garmins or Brytons or even the Magellan Cyclos (not available locally though) are the better choice for dedicated cycling computers. It is a matter of time before Bryton will come out with a unit with map. Smart phones on the other hand will surely be without the altimeter function, except maybe the Samsung Galaxy S3 onwards. This will definitely affects elevation gain or loss readings. There's an example in the net where elevation gain reading are very different where a Garmin was downloaded, the reading was 1,790 meters gain and the same unit downloaded to Strava, it reads 2,615 meters and worse still, Strava on an Iphone the gain showed a massive 3,468 meters
Map for me is important because my courses are all mapped with Garmin Connect after scrutinizing Google Maps and after charting the course, I need the 800 to navigate me through the intended off road or on road course. Actually, speed, and distance readings is secondary to my usage. The elevation and navigation is more important for my usage. So, it differs for road bikers, mountain bikers and other bikers. I have also used the Garmin eTrex 30 on my bike before and after comparisons, the Garmin Edge 800 is more accurate when navigating. Surprising isn't it?
For more info about elevation gain readings,
https://support.strava.com/hc/en-us/communi...468m-elev-gain-