twice by large (120' +) fishing boats on autopilot with no one visible in the wheelhouse or on deck. At least once I was definitely seen by a ship on radar first because the ship's searchlight came on and started poking around in my direction until it spotted me.

That is one of the reasons I emphasize the detection capability of these units - they let you know if someone is in the neighborhood if he has his radar on (provided yours is off....), even if no one is watching it. When you are short handed, the practical reality is that you are not going to have an alert watch 24 hours a day. You must depend to some extent either on devices, or luck. I've been pretty lucky in my life overall, but then I believe that Luck favors the Prepared.

I have paid attention to reflectors I could see - usually on top of buoys - visually and on radar. Sometimes the reflector paints an OK picture. Sometimes you can pick it out once you know its there (because you can see it visually). Sometimes you get no return at all, even close in. All of these reflectors look just like the one you hoist into your rigging. Combined with the many tests that have been done, none of which lend any confidence in the efficacy of a passive reflector, I will continue to turn my transponder on anytime I suspect we are keeping a less than perfect watch.