Just my two cents here but we...the aviation community...should not be test pilots for an aviation safety device.
I feel the manufacturer (FLARM) should have done research on things like antenna placements, especially antenna placements on particular aircraft, to determine what the best solution is.
The quality of the operation of every FLARM unit is essentially a test rig without any quality control or standardization.
The current pool of test pilots has a technological compentency range of top flight electrical engineer to barely able to operate a toaster.

Perhaps organizations, like FAI or SSA or AOPA should step up to the plate and start a controlled process for determining installation guidance for individual planes?
My personal experiences have been frustrating.
Just one example...there are several carbon gliders that I can fly below and behind that never see me on their FLARMS.