Thanks for your comments.
I believe we will go for RA always, and see how it goes in service.
A couple of notes:
1. If you are VFR below cloud and below MSA, an RA will not necessarily only result in a climb for a few seconds followed by a return to previous altitude. If the response to the RA leads to a climb into cloud, you will now have to perform an Emergency Climb to MSA (IMC below MSA = not a good idea).
2. TCAS 1: Provides only information.
TCAS 2: Provides vertical manouevre guidance.
TCAS 3: Is intended to provide lateral guidance also. But is not yet in service, and is unlikely to be so for a long while.