I tried the LP#9 today, very sweet scent. The cinnamon is very pronounced in it. Definitely a great date scent. I think I would have been better off wearing it in the evening though, I got a little bit tired of it after about 10 hours of whiffing it. It seems to have tremendous staying power.
LP#9 is the Penhaligon's scent that is most similar to "department store" fragrances, if I may say so. Opium is similar, I agree. Needless to say, the quality of the LP#9 is very high, but it is not as unique as some of their other offerings.
I went to my local perfume shop and I confirm LP9 is a carbon copy of Yves Saint-Laurents Opium (for men). They may evolve differently depending on your skin, but the smell out of the bottle is awfully similar.