One unresolved problem with TCAS1 in Class G is when encountering another similarly equipped aircraft and you both take the same avoiding action by going to the same altitude
That's true; however from what I have seen, most of the time you see the traffic from a long way out (say 5-10nm) and just do a slight heading change.
It is 99% likely the other chap does not have TCAS and will never know about you. And if you have changed your heading a bit to avoid him, if/when he does spot you he will not need to take any action.
TCAS is not a perfect solution but it is a helluva big help in a lookout, and even then most targets displayed are never spotted
I would never think of using TCAS as a "mad panic" avoidance device in the last few (or few tens of) seconds, which is perhaps the way that big-jet RAs work. In the GA/OCAS context, it is best used from a long way back - in the same way that flying VMC on top enables you to avoid convective buildups from a long way away. The traffic display on the MFD is just another piece of your general awareness of what is around you.