I taught AP Art History with a projector/smartboard combination. The most frustrating part for me was I had one that required cable connections to my computer, and those cables were temperamental, and so it was touch and go every day. The newer smartboards are wired directly. I agree that the colors were not exactly as the original artwork, but neither are old slides and you can't get slide projectors anymore. I loved the Smartboard because you could work directly on it, and you could also isolate certain parts of the painting for students to concentrate on, as well as using just "parts" to show students for them to guess the artist. (there is a way to use a circle to open up wider and wider on the painting, and there is a way to move a section across the painting, and there are ways for your students to come up and draw right on top of the painting, that sort of thing).
Also I had 21 Power points for all 30,000 years of art that I made that coordinated directly with their texts and they could supplement looking at the artwork on the screen with their books.
I gave my students copies of the power points so that they could open them up at home and look at what we discussed in class as well.