It seems extraordinary that a common system is only acceptable if it's yours.
Ah, not so, its not mine, its not yours, it is our regulatory authorities.
It is not me wanting to impose transponders on you, it just so happens that is the only approved system on offer.
Moreover the issue cuts both ways. You could buy a PCAS for couple hundred quid. It runs on two AA batteries and weighs less than a matchbox. I think the unit is cheaper and lighter than FLARM. Have you bought a PCAS?
BTW I will certainly consider a FLARM unit - I am away to have a look at their web site.
In so far as Europe is concerned is it the case that gliders can legally operate in IMC.