“More and more GA aeroplanes are being fitted with glass cockpits now but there doesn't seem to be much on the market that enables traffic.”
Pcas
Flarm
Power Flarm
TM250 Traffic Monitor
Gerrecht ADS-B + Flarm
Trig TA60
Three tecs, some of which are combined into single unit. ADS-B, transponder detection and Flarm. If you do a search this has been covered more recently than this thread. If you have a copy of my article in Flyer some time ago it also covers a test of PCAS, Flarm and talks about ADS-B. There will be an update to this in a few months.
A recent analysis of collisions going back 37 years showed that the risk in the cruse was quite low but the risk joining for a busy fly in are much more significant. A screen display showing 37 threats is probably of little value, but a device saying this aircraft is predicted to hit you in 19sec probably is.
Rod1