What dimension of transparency you are talking about?
It sounds as if you are speaking about internal transparency between the founders and staff, as well as asking about the relationship between the startup and VC/investors. These are two very different things - Investors are going to have a pretty rigid set of expectations that will probably vary from firm to firm - there are probably also certain legal requirements that need to be fulfilled depending on how the startup is structured legally. I can't speak to that specifically because I'm not on the biz side.
Internally, my personal opinion is that a (traditional)startup is built with blood sweat and tears. You can't afford to have a hierarchy of haves and have-nots when it comes to buy in. Everybody needs to have a voice, and everyone needs to be enabled to invest emotionally in the process. You can't buy the kind of passion that comes from being personally invested in a company or project. Lack of transparency internally creates an economy of knowledge power, and puts up walls that don't need to be there. Of course, there are times when some specifics can't be common-knowledge, but I do believe that there should be a culture of openness at a basic level.