I have never flown a 727, but have worked on a few many years ago as an avionics maintenance engineer.

The ones I have seen had the #1 NAV and #1 DME readout coupled to the pilot's HSI, with the #2 NAV and DME coupled to the copilot's HSI. I recall a reversion selector switch, where the #2 NAV could be coupled to the pilot's HSI if needed (for example, if if the #1 NAV failed). I don't recall if the copilot's HSI had that capability

Both pilot and copilot RMIs would simultaneously display the bearings to the VORs tuned on NAV#1 and NAV #2.

In the CS FSX 727, both pilot and copilot HSI's (and their associated DME readouts) appear to couple only to the #1 NAV - though the #2 NAV bearing can indeed be seen on the RMI.

If there is any one thing I would wish for to make the FSX CS 727 "perfect", it would be the ability to see both DME readouts simultaneously - either by being able to fully couple NAV 2 exclusively to the copilot's HSI, or by being able have both DME readouts on the RMI. Most modern RMI's do have that feature, but I do not know if that was the case in the late 1960's-vintage 727 that Captain Sim emulates.

There are many SIDs and other approaches that really do require dual DME capability to be flown accurately.

I have never owned the FS9 version of the CS 727, but from reading old forum posts here, it seems that that one DID have the ability to switch the readout from DME #1 to DME #2, by clicking on the "hold" button on the VOR receiver. I've tried that in the FSX version, but it does not seem to have any effect.

Other than that , I find the FSX 727 a delight to fly - the workload is high enough to keep a flight interesting from start to finish!

Jim Barrett