I have a Zaon PCS in my Maule that I use for aerial photo work www.sfoap.com It is wired into my Garmin 496 so I do not have any wires to my headset. I have had it for several years. It works pretty much as described in the article. I get a lot of false alerts generally showing traffic at my altitude and 1 mile away.
Near a busy airport it can become an annoyance and I have to mute it. The target plane has to have a transponder turned on for the unit to see it so that might have been the trouble with it not seeing the Cessna as he/she might not have had it turned on.
I have a lot of experience with TCAS and this unit is not nearly the same, sort of apples vs oranges. I was working for an airline when TCAS was mandated and all of the pilots I talked to then were sure they would hate it, myself included. But all learned to rely on it and would not want be without one.