I think that a lot of light aeroplanes are flying the PilotAware "amateur lash up built in somebody's shed" and mode-S or ADS-B. Speaking only for my syndicate's aeroplane - TCAS equipped aeroplanes will see our Mode-S, but we'll see just about anything with the PilotAware. Not mind you disputing that PAW is a lashup: getting it faintly neat and tidy in our cockpit was quite a challenge (although we managed, and obviously don't have much by way of classified wiggly amps!), it's an uncertified (and uncertifiable for now) system, and that's a problem. On the other hand it's available, affordable for people spending their own money, and does appear to work.
Anything, thanks those who have contributed what military aircraft are outputting - from responses above I make that...
Conspicuity
BBMF - FLARM, (Mode-S?)
Typhoon - ADS-B
Seeing
BBMF - FLARM
Air Cadets - FLARM
Tucano - TCAS 1
RAF Heavies - TCAS I or II
Tornado - ACAS(?)
Typhoon / Lightning - Primary radar
Is that correct? There are gaps there clearly - presumably the heavies all have ADS-B?
What are the rotaries carrying?
G