One needs to consider the final beer character and how to get there. The Crystal Police always say no more than 5%. I think that comes from IPA, where the sweetness and dark fruit of some crystal clash with the hops. I did a dark Czech lager for NHC. I did get some criticism from the masses, more on how the accent on Lezak should have had the upside down carrot. Some had studied in the Czech Republic, so they knew the language. Then I would ask about the beer, and they would say it was really representative. It had 15% Weyeramann Carabohemian. I had that style of beer, a Kozel at the PU brewery, and I said dang that beer was really close!
Think about the final beer, the ingredients, and the process that will get you there.