I know there are different schools of thought on this, that asking her out puts the interaction in a very formal frame where you are after the prize (her) as well as invoking any experiences she has with 'dates' in the past
On the other hand, one of the tenets of tyler durdens methodology is to always be willing to break your own rules
I've been told (including by a natural I know) things like "you'd have to date her to get anywhere". The biggest advantage I see is that it's a sure-fire way to declare your intentions up front, and if nothing else, avoid a LJBF.

Having said that, my question is this: Would you ever ask an HB out for dinner. coffee, whatever, but with the explicit mention that it is a date?