I'm afraid that within the EU you will probaby face the same confusion that you get when you ask two different FSDO's the same question.
If you look at ICAO Annex 1
http://dcaa.slv.dk:8000/icaodocs/An...Personnel Licensing - 10th ed - July 2006.pdf
Go to Chapter 6 to see medical certificate requirements. specifically, look at paragraph 6.1.1 Which states if you are an ATP you need a 1st Class medical.
For duration of the 1st Class look at Paragraph 6.3.11 which references Paragraph 1.2.5.2 Which states that the 1st Class medical is valid for 12 Months.
Paragraph 1.2.5.2.2 goes on to modify the requirement for anyone who has passed his 40th birthday by reducing the validity by 6 months (to 6 months) for a pilot. Same is true for a pilot who is age 60 or older (1st class valid for 6 months).
So it looks like the FAA's new rule extending a 1st class medical to 1 year for pilots under 40 was to bring the US into harmonization with ICAO. As far as a second class medical being as good as an ICAO 1st class??? My guess is that the inspector doing your SAFO will only know enough to look for an "I" in the appropriate box.
If you were to ask me, I think that if you were over 40 you need to get a 1st class every 6 months. If you are under 40 you are good for 12 months.
However, every country may interpret this differently (look at the disparity of opinions in our own FAA). Your best bet would be to ask your handler. Remember when France was interpreting cabotage rules differently from the rest of the EU? We actually ended up "importing" our aircraft into the EU to avoid hassles with the French just over that one difference in interpretation.