Hi,
I am new here so certainly no expert, but I am in the UK if that helps.
I see no reason why it would not work as we have managed to use EU discs sucessfully in imported japanese cars hat have run japan's version of pioneer head units without any problems.
They need a frequency expander due to the difference in their broadcast radio stations, but the US uses the same frequencies as the uk.
There is a huge price difference (like double) and we have to pay for the ipod adapter separately, but we do get the bluetooth module and according to the pioneer uk website, the manual for the D3 at least indicates that we have RDS on ours, whereas I don't think the US version does.
Until my own one arrives shortly, I can't confirm if this is the case. I have to wait about a month.
Make sure you let your EU friend know, as I would be really p'd off at the lack of RDS.