Copter-4.1.2 has been released as the stable version and can be downloaded using MP or QGC or downloaded directly from firmware.ardupilot.org.
The changes vs 4.1.1 are in the release notes and copied below
Changes from 4.1.1
- CAN_Dn_UC_OPTION param added to help resolve DroneCAN DNA conflicts
- Durandal with alternative ICM-20602 IMU
- OBAL autopilot support (Open Board Architecture for Linux)
- FETtec One ESC protocol support
- Bug Fixes
a) ADSB vertical velocity reporting fix
b) APM/LOGS directory creation fixed on some boards
c) AutoTune fix to disable SMAX limits that could interfere with tune
d) EKF3 fix to switch to non-zero primary core when disarmed
e) Notch filter update rate fix
f) Surface tracking fix if rangefinder glitches
g) TradHeli rename of H_COLL_HOVER to H_COL_HOVER
We didn’t get a lot of feedback on the 4.1.2-rc1 beta release but hopefully this is because nobody found any problems and Plane users have already been flying most of this code for a couple of weeks. Still, please tell us if you see any issues.