Firstly, the blank keys shouldn't be a problem as long as you are a TRUE touch-typist. If you want to try out whether you'll have big issues, try programming in the complete dark and see how much you have to search for the keys. This is a very personal issue, and I personally don't have an issue with blank keys, but most people DO have problems when they use my blank keyboard.
As for the DAS Keyboard, I don't have experience with this model in concrete, but due to the high build quality and the use of true mechanical switches with damping, they keyboar*should*d remain completely quiet for it's lifetime. Just remember that only diamonds are forever.
Keep us updated if you do end up purchasing this model!