I sent an inquiry to AOR USA regarding the operation of the ARD25 with my forthcoming AR8600. Here is a snippet of their very quick response:
"Regarding the APCO25 reception, no modification will be necessary to the AR8600.
What you have to to is to set the receiver in the WFM mode. Once connected to the
ARD25, the ARD25 will automatically decode signals. If the signal is a normal NFM signal (no APCO),
then receive audio (in the NFM mode) will be heard from the internal speaker of the ARD25.
Therefore, there is no need to switch the AR8600 to the WFM mode or NFM mode back and forth."
I'll probably take the plunge and try one out...any other brave souls?