Kos's comments and my reply.
Quick summary: No, I don't think exit polls are necessarily better and, in any case, I don't yet have the raw exit poll data. But I did have the raw data from the Pew polls, so that what I used. Pew polls are good. But Kos did get me on New Hampshire. As we continue to analyze further data, I don't think our maps will change by much but they will certainly change in some details (notably, whites in N.H.). Also, now I'm convinced that it's better to use some range of shading to indicate the close calls, so that people don't think I'm expressing 100% confidence in the color of each state.