DCs have a reputation of being incompatible with both DCs and other headsets. This is due to the difference in current required by different headsets for their amplified microphones to operate.
The problem is strictly spoken not caused by the headsets themselves, but by the way the aircraft is wired/equipped. If both microphones are supplied from the same supply line (as is normally the case if the intercom is run off one of the com boxes), the mismatch in current requirement often means that one mic either does nothing or sounds very distorted.
If on the other hand a decent panel mount intercom is used, each microphone has its own supply line and as a result the difference in current requirement is no longer an issue. Add to this the fact that you now have a squelsh as well on your intercom I'd say this is the preferred method of solving the incompatibility issue.
AFAIK, the current required by all DC microphones falls within the applicable limits set out in some FAA document. Therefore they don't regard it as their problem that this issue exists, and will always point to the aircraft installation if complaints are received.
So, the answer is to look for the panel mount intercom (sigtronics etc) and you'll be fine with any combination.
Price of spares: not cheap. For instance a lead with plugs is around 50 GBP. However, the build quality is superb and as long as you don't squash the lead in the A/C door you should never need to replace it.
What the older DCs (the ones with the brass plugs rather than the newer nickel(?) plated plugs) do occasionally need is a good clean of said plugs. Bit of steel wool to make them nice and shiny again seems to do the trick and has a positive effect on their performance.
Hope this helps.
Gerard
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