TCAS is a help but not a panacea.
Before being exposed to it I was playing with the idea of getting one of these handheld TPAS units.
Would not bother now as:
1. In the open FIR (where you are least likely to have a meaningful service) most bogeys will not have a TXPDR so they are not going to show up anyway.
2. Without azimuth and bearing information you will just get worried sick, swivelling your head in any direction to find it, potentially interrupting a 'good can' and detracting from conflicting traffic in your path.
When not able to get a RIS/RAS in the open FIR it still pays to talk to a meaningful station as most sensible people will do the same.
FD
PS: Relying on quadrantals for protection is the same as trusting the 'big sky theory'