'Funny how frags are so different for each of us. I find absolutely no resemblance between Arpege and Opium.
Matter of fact, Arpege is one of the most vile frags I have ever worn and is assuredly in my top 3 worst scents of all time. Opium is one of the best frags I own.
I wear the EDP version of Opium and it is excellent. There are past threads stating the similarities between the EDT & EDP. Both are good to go. If you are ho-hum about the EDT version, chances are the EDP will impress you a tad more, but probably not enough to warrant a purchase.