To my knowledge, Frog Morton Across the Pond no longer contains Syrian.
I'd encourage folks who've never had Syrian latakia to not let their tins age too much. In my experience, Syrian fades faster than Cypriot leaf. The flavors and floral aromas are far more delicate in Syrian.
Also be aware that vintages matter. I've honestly never had any Syrian that could compare to the leaf that Pease used in his Syrian blends. Even though other blenders bought that same leaf, their supplies have been aging for 15 years and the leaf today simply isn't the same. It's also easily overwhelmed if there's a large portion of Cypriot in the blend as well. Which means you won't get much Syrian flavor in a bowl of Gordon Pym; it'll be more prominent in, say, Brebbia's Preludio Mixture No. 60.
Just my personal take...