I see that this is all a bit of smoke and mirrors. ATC won't say "121.5", instead they will say "121.505" (i.e. the even 25kHz frequency names won't be used), even though the radio will actually transmit/receive on 121.500 MHz. So all of you who have been asked in the past to monitor 121.5 will now have to monitor "121.505".
Similarly, you can't select "118.25" on your radio. You select "118.255" which is really frequency 118.25 MHz. Then when you fly to the US you will have to add 0.005 to each frequency assignment. Except for VOR/ILS?