VT1,
Depends if you feel the safety is gap is best filled with you being aware or others being aware of you. With a PCAS setup you don't need a transponder so you deal with significant amount of the first former. By fitting a transponder you deal with a minority of the latter.
If anything, without a transponder you don't suffer the nuisance alerts that I mentioned earlier.
Lights are questionable. In bright daylight strobes don't seem to be that visible. Not sure about the new LED ones.