I’ve downloaded 2 Xert apps from the Android Play Store: V 3.5.5.0 (185) and V 4.2.0.0 (225). I started using the V 4.2 first. I liked the heads up of upcoming intervals, estimated mph and distance based off my Stages power meter, and it found and didn’t lose my HRM connection. The only issue I had with it was I couldn’t find a way to calibrate my power meter.
I switched to V 3.5.5 because I can calibrate the power meter, but my HRM connectivity is spotty and I lost the mph and distance estimates.
Xert Mobile (XM) is the original Android app from some years back.
Xert EBC is the new version which has most of the features of old app plus some new ones such as Sessions support.
You should not need to calibrate your power meter as powermatch is automatic with EBC.
EBC will eventually replace XM once all the core features of XM have been added.