It is a lot of crystal but it's a fabulous recipe. It suggests tastes notes of nuts, vanilla and chocolate and it's all three of those.
I made one last Christmas and have just done another for this Christmas (albeit with fruit in this year).
Go for it!
David
Evolution didn't end with us growing thumbs.
Bill Hicks
I have done a mild with 25% crystal and came out very nice, no hesitation about making it again. I did make it stronger than your recipe though, a bit over 4%.