What you do is up to you, and see best at the time. The "problem" we are discussing is what we as a community advise you do, both in actions, and in equipment terms... and that carries the liability of ensuring the advice is truly fact based and risk free. TCAS has had a tough learning curve, and nobody wants to repeat that in a far less trained for / regulatory environment.
I guess this encapsulates the point I was seeking to make. Your reaction was based on your ops manual and your training operating in a controlled enviroment using TCAS which provides a RA.
CAS typically used in GA does not provide an RA. Much of the time (given that most GA pilots spend most of their time outside CAS) the flight is neither at an asigned altitude or heading.
In short the pilot is "free" to do as he wishes.
To take the discussion a step further. With TA it is usually possible if you wish to establish vertical seperation of 1,000 feet and lateral seperation of 5 miles when the traffic first appears and well before any collision threat exists unless of course the system is vertically inaccurate by a least a 1,000 feet and inaccurate in distance by more than 5 miles and in bearing by more than 90 degrees. A miss is a miss but given the limitations of the system I am not sure on the desperate need to acquire the traffic given the very different constraints and speeds applicable in the enviroment we are discussing.
I agree, there may be an element of rewriting the manual but I would prefer to consider doing so rather than blind obedience to a procedure that has been inherited from a different enviroment.
I appreciate your comments about the way in which you would react. Your experience is interesting.
However I note that you have not responded to the specific example of two aircraft in open FIR in IMC. You will never acquire the traffic visually. The decision is simple. You avoid the traffic using the TAS before it remotely becomes a threat or you wait unitl you receive a traffic warning. I know whcih course I would prefer to follow.