SS, I can't really agree with your example of the unseen sailplane in cloud as an argument against the fitting conspicuity equipment, surely it is an argument FOR fitting it to all aircraft that operate in IMC? Actually, this was the basis of another discussion here some time ago (which went on for ages)! At least one glider pilot voiced the opinion that everyone should fly around on "his" glider frequency whilst in IMC, even to the detriment of obtaining an ATC service elsewhere, just in case he might be gliding in cloud, which he rarely did, on his day off.
ST
I wasn't using that example as an argument against anything. It was to illustrate the danger of assuming that non transponding aircraft are likely to be low and slow and in VMC.
I'm still amazed that nothing small and lightweight can't be thought of. What BackPacker suggests would be fine ... BUT NOBODY HAS INVENTED ONE! When they do, or they develope a better system, I'll sign up straight away. I'm not so stupid as to gamble with my own life just to make a point. I'd love a foolproof avoidance system that I could fit. As it stands, no such system exists
SS