I did this recipe (the traditional version) about 2 months ago. Didnt decoction, but mashed around 154 instead. I didnt have a way to keep it chilled for aging, so I left it at room temp and let it do its thing and when I checked the gravity on it recently it was at 1.000 !!!
I have no clue how a 1.100 OG beer finished at 1.000 but I'm thinking this beast is going to need some serious aging.