Rover-4.1.1 has been released as the official (default) firmware for rovers and boats and can be downloaded using various ground stations including MP and QGC and it is also available directly from firmware.ardupilot.org.
Changes vs 4.1.0 are in the release notes and copied below:
- EK3_PRIMARY allows selection of which EKF core/IMU to use on startup
- Bug Fixes
a) MAVFTP init fix (could cause slow parameter download)
b) Scripting fix when logging strings
c) Serial flow control fix (affected at least Lightware LW20 serial lidar)
d) QiotekZealotF427 IMU (ICM42605) orientation fixed
Also for those who compile their own firmware at times, github made a change affecting submodules (blog post here) so the Rover-4.1 branch includes the new submodule-sync.sh script that may help you if you have troubles.