4) flarm uses consumer grade electronics for the essential radio data link - which neatly explains the low cost - if comms fail, again there's nobody to blame.
All in all, flarm offers worthwhile information with perhaps 90% availability, and nobody should reject it - the danger is to believe in it 100%.
Jan, for me any collision avoidance equipment I use (I have an old Xaon MRX) is used IN ADDITION to other methods of detecting traffic - for example, my primary means of seeing and avoiding will always be using the Mk 1 eyeball of myself and other passengers; on top of that I regularly request a traffic service - whether I get it when in the UK is another story
So, put in that context, I'd rather have a piece of equipment with me with consumer grade electronics in it which MIGHT fail as part of an extending net to help find and avoid traffic than rely on just my eyes solely - after all, if it points out conflicting traffic which I've not seen, then it's done it's task......