I have mixed feelings about this issue. Before we rush into the "yes/no" debate, we have to acknowledge first that there are two main groups of LEED users- the ones who are slightly involved, and the ones who are deeply involved. For the first group, credits shortening is pure jargon. I have received strange looks from clients when I referred to the energy modeling credit as EAc1. On the other hand, between contractors and colleagues, having a short form of the credit name is very helpful in communicating what you are talking aboout. To sum up, I believe we must have some form of shortening (after all, that's very popular on Twitter and other social networks), but we have to use it carefully, specially with people who is not familiar with the certification system