The GMU 22 is a derivative product of the TSO'd GMU 44, which has its roots in certified installations. The GMU 44 is used in aircraft all the way up to midsize business jets.
To offer a magnetometer at a very competitive price, Garmin's Team X designed the GMU 11 from the ground up as a light-weight, low-cost magnetometer specifically for the E-AB market. More recently, the GMU 11 has been certified with the G5 in an AML-STC for many Part 23 aircraft.
One advantage of the GMU 11 is being able to mount it with the connector facing any one of the 4 cardinal headings. The GMU 11 interfaces on the CAN bus and works with both the G3X or the G5. The GMU 22 connects directly to the GSU 25 (or our legacy GSU 73) and will not interface directly to the G5.
Based on our testing, both units provide excellent performance
Hopefully this is helpful in your decision making.
Thanks,
Levi Self
Team X Project Manager