Would it be possible or practical do have an adjustable delay between the two signals in Diversity reception? My thought is that different antennas may respond to different propagation modes which might have slightly different propagation times.
My understanding is, currently, DR is implemented for polarization diversity only, so the difference in propogation time between two antennas in your back yard would be less than nanoseconds. I think, by contrast and what Steve has talked about some is geographic DR would be, likely, a delay which is one of the motivations to have GPSDO installed to sync the two signals. Are you noticing a delay? I wouldn't think sub nanosecond would even register in the human brain. But then I didn't spend the other $4,000 to find out either. I believe geographic DR would be supported in the 6500 as one of the signals would be via IP, which would inject it's own delay.
I've been reading in the new ARRL book, "Propagation and Radio Science" about the X and O waves that are circularly polarized, but different handed and I was thinking about trying two different CPOL antennas in diversity mode. According to the book, the propagation delay is different with the O wave usually arriving first.
Right now, I only have two vertical antennas, so I'm not getting much advantage with DIV.