I have my relatively light Garmin Inreach mounted on that cross-bar. It vibrates quite a lot when I hit the gravel. It made me nervous enough to eventually get a Camel Adv brace this week (not too painful on the wallet as it was on discount).
Today I tested it out for the first time, and it is rock solid. Good product! I should have fitted one looong ago.

I reckon it is strong enough to carry multiple GPS's, and I may mount the Montana there.

Anyone who takes their AT off pavement should seriously consider to beef that bracket up IMO.