Glad you like the Racing, Hysteria! I'm enjoying my reintroduction to Caron Pour Un Homme today, which I received from you yesterday in the swap for the Racing.
I find that Racing is spicier and Opium is sweeter. But the main difference when I wear them is that the Opium has great sillage and longevity while the Racing (as great as it smells) disappears rather quickly, no matter how much I put on. That was a major disappointment for me especially since it was great on the cardboard.
I do find a major similiarity between the Opium EDT and Penhaligon's LP#9 for Men. I received a sample of the Penhaligon's in a swap with Francois last year, bought it in Saks and it promptly became one of my favorites of all time - it also has great sillage and longevity when I wear it.
I can't understand how I never bought Opium all the years it was out. I got it a few months ago in a swap with Francois (thanks again!) for Penhaligon's Endymion (another one which promptly disappeared after I put it on) and it too became one of my all time favorites.