It's really a fantastic fragrance this one, no? Regarding the longevity, I take it you're sure you tested vintage EDT and not EDC? I'm rather fond of current formulation EDT but it tends to turn sour on me for a while. Once the powdery leathery drydown kicks in everything's okay again. I don't really understand what you mean by vertical vs horizontal, unless you mean that the current formulation is linear, i.e. no changes in the fragrance other than it becoming weaker?
I'm trying to source a nice bottle of vintage EDT though I also almost pulled the trigger on a vintage bee bottle of EDC.