My advice from the DoD guys in Woomera is that Iridium is the only network without "black spots" down here. On the basis, I bought 2 Motorola 9500's.
I would upgrade to the 9555, but it doesn't seem to be any better in terms of connectivity and not smaller enough to make a difference. They came with the earphone / mic wired handsfree units, so I assumed it might plug straight into the Bose A20 (its not 6.5mm. the standard is either 3.5mm or 2.5mm - I forget). My Bose A20 is in my car, which is currently locked in the hangar because I did a one way trip to the LAME. I'll try it tomorrow