1996 #1531 52.2% vs 1997 #91 58.4%
Overall I prefer the #1531 slightly due to the freshness on the nose. Both have equally good body on the palate.
Both very similar in some ways, with #1531 fresher on the notes, more on fresh and juicy fruits while the #91 is heavier on dried fruits and more oaky and dark chocolate. Some nice honey for the #1531, with a sweet and floral background. After sometime, the fruits started to come alive for the #91, and some vinegar and slight bit of ginger. Some nice vanilla come in for the #1531.
Overall the #1531 is fresher and lighter, while the #91 is heavier and stronger.
#1531 - rather bright, clean and oily. Nice resinous sweetness, tropical fruits, red fruits, taste like a PX cask to me. A little bit of dark chocolate and ginger.
#91 - more oaky, similar sweetness, more on dark chocolate and mixed nuts. More powerful, with lots of herbs and spices.
#1531 - nice fruity finish, not very long but very refreshing. Some orange peel and ginger.
#91 - nice length, with more oakiness and tannin. Slightly dry, and nutty.