I believe, the FAA believes, that ADS-B is the way of the future. I don't think FLARM can see ADS-B out traffic. Having a ADS-B receiver in a sailplane is a relatively cheap way to identify traffic conflicts. I know that in the US most sailplanes are not equipped with transponders and/or FLARM. ADS-B is going to be universal by 2020. I think even sailplanes will require to have ADS-B out soon. The Garmin product is much cheaper than FLARM and perhaps far superior. The future of FLARM is in question, I think.

Midairs involving sailplanes are very rare but that is entirely due to the fact that sailplanes themselves are becoming rare.

The GL 39 sells for about $700, and it can interface with many devices. I plan to buy a certified flight recorder and I was wondering if there is one that can be used as output for the GL 39 (in addition to serving as recorder).

A lot of what you're saying here Ardi indicates that you're not caught up.

In the US, we use a version of Flarm called PowerFlarm. It is quite widely adopted by the population of glider pilots that fly actively in the US. PowerFlarm does indeed have ADS-B receive built-in. It works great and integrates perfectly with flarm target indications. PowerFlarm has an approved flight recorder built-in as well. It also has a transponder detector function that picks up aircraft that have a transponder but no PowerFlarm nor ADS-B.

Get PowerFlarm and your glider will be on the network -- detectable by the rest of us and you won't need to buy a separate recorder.