OAP, the point I'm making is that if I knew I was in a situation where I'd no intention of following an RA, I'd go 'TA only'. Exactly as the designers of TCAS decreed and why they put a TA only option on the box! If you're not going to follow the RA (why?) you should be in TA only!
Now, A few examples of when I'd go TA only.
1. Airways transit to Southwold (TA/RA), descent into formation hold then flypast (TA only). Flypast complete, split & rtb (TA/RA)
2. Transit through CAS along a defined mil corridor with numerous other mil AC at similar alt (TA/RA). Faster mil aircraft closing to pass at same alt and less than 1nm, (TA only)
3. Visual circuit when routing downwind to Initials (TA only)
4. Recovering to Cranwell from complex sortie (TA/RA). Joining TACAN hold with numerous Tutors, KingAirs etc in vicinity (TA only)
5. Supersonic airliner loitering at 2000ft overhead Leuchars waiting 15 min for the Red Arrows to appear (TA/RA). A Tucano calls visual and asks to format in fighting wing on said airliner ( TA only)