Currently you can choose DEM, GPS or Barometer as your altitude data source. But there is no "combined mode".
Especially phones with a barometer could use the sensor to correct GPS heights. A combined GPS + barometer mode would be benefitial for height accuracy and make height smoothening by filters (which is the current height "correction" method) obsolete.
I know it is possible to recalibrate the barometer automatically once per hour, but i would prefer a smarter and more regularly executed recalibration based on the current gps accuracy. This avoids recalibration in inaccurate terrain (inside buildings, tunnels, cliffs during steep climbing).