Is the absence of an altimeter in the forerunner 245 music a deal breaker?

So I have to choose between the vivoactive 4 and the forerunner 245 music. I am a casual/amateur trail runner and I do swimming. Both of which the forerunner seems to be more equipped for however the absence of an altimeter is very frustrating for a trail runner and I also hike a lot. I also want a watch with music abilities. 

So:

1. Is the altimeter in the vivoactive accurate enough to rather buy it over the forerunner 245? 

2. How accurate is the elevation correction on software like garmin connect and strava? 

3. What would you recommend between the two or in that price bracket?

  • Barometric altimeter is useful if you want to have accurate altitude CHANGE data (like for example grade, or total ascent/descent), and not necessarily the most accurate absolute altitude data at a given moment. Going back to your questions:

    1. It's as accurate as barometric altimeters go. Due to the barometer port design in a wearable device, it might be susceptible to clogging (and thus producing totally wrong numbers).

    2. It is relatively rough. It varies depending on location, can have severe errors in some locations, does not take into account man-made structures.

    3. For a trail runner I would recommend the 245.