I had thought it would somehow automagically select the better antenna for receiving, but it looks like it wants me to make that selection myself. So, this may work better with longer preambles I suppose, to give enough time to measure the RSSI on each and then decide.
I suppose an easy solution would be to have a remote node send repeated packets, and I just program the RFAxis to toggle between its two antennas after allowing sufficient dwell time per antenna. That way it's more likely to receive at least one of the packets.
All in all, though, I think maybe having two separate radio receivers (since they're cheap anyway) for a gateway is probably better than having one radio receiver, with the burden on the firmware to select which antenna to receive on.
Any thoughts on this?