The problem with TCAS is that most GA traffic is below 2000ft, most of it is nontransponding (due to lack the transponders, due to ignorance, or IMHO often deliberately), and while above that level most traffic is transponding there is very little of it.
All UK midairs in past 10 years have been below 1000ft, and you will never find me below 1000ft except when landing
I have been very tempted to spend the ~ £15000 on the Avidyne 600 kit but can't justify it relative to the levels I fly at (highest possible OCAS, generally), the heavily slanted vertical distribution of UK GA traffic, the utter scarcity of GA outside the UK, and to the appalling levels of UK avionics shop "expertise" in taking the aircraft apart and putting it back together again correctly. TCAS is a major wiring job, to say the least, and can't be entrusted to the usual butcher.
Of course one can't put a value on one's life so I will never argue with those who want to install it. But, UK OCAS, it will miss the majority of traffic, because Mode C transponders are not mandatory.
Re routing via common navaids, it's better to take a shortcut around it.