I just cracked a 6 month old extract based Belgian Dubbel. Recipe made to 13L, about 6.9% abv:
1 x Thomas Coopers Pilsener
250mL Belgian Dark Candii Syrup
500g Dextrose/Maltodex mix
Wyeast 3787 Trappist High Grav Yeast
It tastes fantastic, 'sweet' when first put in the mouth but finishes dry...