Hey Eoin, we at SMHI have done this in the field as a comparison. All FlowTrackers at the same time, last year 2023. Once back in 2013, I drove all of them in a boat on a lake and compared the velocities. I rigged them up in a ladder.
Please also try the new forum at https://forum.internationalhydrometrygroup.org/
if it doesn’t work try http instead of https