It will probably be no surprise to some to hear that I have a Zaon XRX PCAS in the V-tail. I bought it after the nearest near-miss I have had in 35 yrs flying.
It appears to work well once you have it set up right.
Is it worth the money?? Don't know - I guess if it stops you having a mid-air it is worth every cent.
Remember though - it is only passive! Relies on the traffic's transponder being pinged by SSR or another aircraft (RPT?) with an active system.
Dr 