Dan -

The statistics show over and over that glider-to-glider collisions are more of a threat than glider-to-GA/Miliatry. FLARM isn't intended to be a perfect solution; it's intended to provide a very reliable, medium-cost, low-power solution for the biggest collision threat: other maneuvering gliders.

Mode C and even Mode S systems are not well-suited for combating glider-on-glider carnage when the craft are in close proximity and maneuvering.

There simply is no perfect solution; but I for one will take the single solution that reasonably covers the broadest range of targets and situations - and right now that's a PowerFLARM.

--Noel