I think it depends on which headset you have. See
http://forums.flyer.co.uk/viewtopic....hlight=#375353
and
http://forums.flyer.co.uk/viewtopic....er=asc&start=0
for some further discussion.
I have also had pms from dealers saying they are trying to get the problem resolved by ICOM UK who are waiting for Japan.
If you want to buy one then I suggest you take your headset along and try it in the shop. Make sure you press the PTT on the headphone adapter as pressing the one on the side of the radio activates the mic in the transceiver rather than the one in the headset.
Just a warning, as I bought mine by mail order and by the time I found this problem I was into the repair rather than refund timescales and ICOM do not have a repair available yet.
More annoyingly they do not answer emails or letters.